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NAME

       pppd - 点对点幸槭鼗そ

 SYNOPSIS
       pppd [ tty_name ] [ speed ] [ options ]

述
       点对点幸           (PPP)          提供一种在点对点串列线路上传输资料流
       (datagrams)的方法。PPP是由三个部份所组成的:一个在串列线
       路上封装(encapsulating)资料流的方法,一个可延伸的连结控制            -
       定(LinkControlProtocol:LCP),以及一些用来建立并配置不        同网路层-
       定的网路控制卸(NetworkControlProtocols:NCP)

       封装的机制(scheme)是由核心中的驱动程式码来提供。pppd提供
       基本的LCP,验证(authentication)的支援,以及一个用来建立
       并配置网际网路卸(InternatProtocol(IP))(叫做IP控制 卸ǎ琁PCP)的NCP。

 FREQUENTLY USED OPTIONS
       <tty_name>
               在该名称的设备上进行通讯。如果需要的话可以前置一个
              "/dev/"字串。如果没有给设备名称,pppd将会使用控制
              台的终端机(controllingteriminal),并且产生(fork)出
              来时将不会把自己放到背景去。

       <speed>
               将波特率设为speed。在像是4.4BSD以及NetBSA的系
              统上,可以指定任何速率。其他系统(e.g.SunOs)只允
              许有限的几种速率。

       asyncmap <map>
               把非同步(async)字元设为对照到。这个对照表
              描述哪些控制字元不能在串列线路上成功地接收。pppd将
              会要求彼端以两个位元组的逸出序列(escapesequence)来
              传送这些字元。其参数是32位元的十六进位数字而每个
              位元代表一个得避开(escape)的字元。位元0(00000001)
              代表字元0x00;位元31(80000000)代表字元0x1f或
              是^_。如果给了多个asyncmap选项,这些数值会以逻                -
              的或(OR)合在一起。如果没有给asyncmap选项,将没
              有非同步字元对照表会被加以猩汤吹家邮铡U庋硕
              将会避开所有的控制字元。

       auth   要求彼端在允许传送或接收网路封包之前先验证它自己。  This  option
              is the default if the system has a default  route.   If  neither
              this  option  nor the noauth option is specified, pppd will only
              allow the peer to use IP addresses to which the system does  not
              already have a route.

       call name
              Read  options  from the file /etc/ppp/peers/name.  This file may
              contain privileged options, such as noauth, even if pppd is  not
              being  run  by  root.   The  name string may not begin with / or
              include .. as a pathname component.  The format of  the  options
              file is described below.

       connect script
               使用以所指定的可执行指令或是shell指令来设定
              串列线路。这个指令稿一般会使用"chat"程式来拨数据
              机并开始远端ppp区段作业(session)。  A value for this option from
              a privileged source cannot be  overridden  by  a  non-privileged
              user.

       crtscts
              使用硬体流量控制(i.e.RTS/CTS)来控制串列埠上的资料流。 If neither
              the crtscts, the nocrtscts, the cdtrcts nor the nocdtrcts option
              is  given, the hardware flow control setting for the serial port
              is left unchanged.  Some serial ports (such as Macintosh  serial
              ports)  lack  a true RTS output. Such serial ports use this mode
              to implement unidirectional flow control. The serial  port  will
              suspend  transmission  when requested by the modem (via CTS) but
              will be  unable  to  request  the  modem  stop  sending  to  the
              computer.  This  mode  retains the ability to use DTR as a modem
              control line.

       defaultroute
               当IPCP猩掏耆晒κ保黾右桓鲈ど璧菟吐肪兜较低
              的递送表,将彼端当作闸道器使用。这个项目在ppp连线 中断後会移除。

       disconnect script
               在pppd已局战岣昧咧嶂葱幸运付ǖ目芍葱
              指令或是shell指令。这个指令稿可以用来,例如,如果
              硬体的数据机控制信号无法使用时,发出指令给数据机使  其挂断电话。
              The  disconnect  script is not run if the modem has already hung
              up.  A value for this option from a privileged source cannot  be
              overridden by a non-privileged user.

       escape xx,yy,...
               指定在传输上确实应该要避开的字元(不管对方是否有用
              它的非同步控制字元对照表要求避开它们)。这些要被避
              开的字元是以用逗号隔开的一串十六进位数字指定的。要
              注意到几乎任何字元都可以用escape选项指定避开,不
              像asyncmap选项只允许指定控制字元。不能避开的字元
              是那些有十六进位值0x20-0x3f或是0x5e者。

       file name
               从档案里读取选项(其格式叙述在後) The file must be readable by
              the user who has invoked pppd.

       init script
              Run  the  executable  or  shell  command  specified by script to
              initialize the serial line.  This script would typically use the
              chat(8) program to configure the modem to enable auto answer.  A
              value for  this  option  from  a  privileged  source  cannot  be
              overridden by a non-privileged user.

       lock   指定pppd应该在此串列设备上使用UUCP式的锁定以确
              定对该设备为互斥(exclusive)存取。

       mru n  把MRU[MaximumReceiveUnit最大接收单元]的值设为          n来进行-
              商。pppd将会要求彼端传送不比位元组
              更长的封包。最小的MRU值是128。预设的MRU值则是
              1500。对於慢速线路上的建议值是296(其中40个位元
              组给TCP/IP表头+256个位元组的资料)。
               (Note that for IPv6 MRU must be at least 1280)

       mtu n    将MTU[MaximumTransmitUnit最大传输单元]的值设   为n。除非彼端-
              由MRU猩桃笠桓龈〉闹担琾ppd
              将会要求核心网路程式码透过PPP网路界面所传送的资料
              封包不超过n个位元组。
               (Note that for IPv6 MTU must be at least 1280)

       passive
               在LCP中开启"passive"选项。加上这个选项,pppd将
              会试图初使一个连线;如果没有从彼端接收到回应,那麽
              pppd将只会被动地等待从彼端所传来的一个有效LCP封
              包(代替结束离开,就像它在没有这个选项时所作的)。

 OPTIONS
       <local_IP_address>:<remote_IP_address>
               设定本地以及/或是远端界面的IP位址。两者之中的任
              何一个都可以省略。该IP位址可以利用主机名称或者是
              十进位数值加小数点符号指定(e.g.150.234.56.78)。
              预设的本地位址是系统的(第一个)IP位址(除非有加上
              noipdefault选项)。远端位址如果没有在任何选项中指
              定的话将从彼端取得。因此,在简单的案例中,这个选项
              不是必须的。如果有一个本地以及/或是远端的IP位址
              以这个选项加以指定的话,pppd将不会接受在IPCP猩
              中从彼端所传来不同的值,除非加上ipcp-accept-local
              以及/或是ipcp-accept-remote选项,个别地。

       ipv6 <local_interface_identifier>,<remote_interface_identifier>
              Set  the local and/or remote 64-bit interface identifier. Either
              one may be omitted. The identifier must be specified in standard
              ascii  notation  of  IPv6  addresses  (e.g. ::dead:beef). If the
              ipv6cp-use-ipaddr option is given, the local identifier  is  the
              local  IPv4  address  (see  above).  On systems which supports a
              unique persistent id, such as EUI-48 derived from  the  Ethernet
              MAC address, ipv6cp-use-persistent option can be used to replace
              the ipv6 <local>,<remote> option. Otherwise  the  identifier  is
              randomized.

       active-filter filter-expression
              Specifies  a  packet  filter  to  be  applied to data packets to
              determine which packets are to be regarded as link activity, and
              therefore  reset the idle timer, or cause the link to be brought
              up  in  demand-dialling  mode.   This  option   is   useful   in
              conjunction with the idle option if there are packets being sent
              or received  regularly  over  the  link  (for  example,  routing
              information packets) which would otherwise prevent the link from
              ever appearing to be idle.  The filter-expression syntax  is  as
              described  for  tcpdump(1),  except  that  qualifiers  which are
              inappropriate for a PPP link, such as ether  and  arp,  are  not
              permitted.   Generally  the filter expression should be enclosed
              in single-quotes to prevent whitespace in  the  expression  from
              being  interpreted  by  the shell. This option is currently only
              available under NetBSD, and then only if  both  the  kernel  and
              pppd were compiled with PPP_FILTER defined.

       allow-ip address(es)
              Allow  peers  to  use  the  given  IP  address or subnet without
              authenticating themselves.  The parameter is parsed as for  each
              element of the list of allowed IP addresses in the secrets files
              (see the AUTHENTICATION section below).

       bsdcomp nr,nt
              Request that the peer compress packets that it sends, using  the
              BSD-Compress  scheme,  with  a maximum code size of nr bits, and
              agree to compress packets sent to the peer with a  maximum  code
              size  of  nt  bits.   If nt is not specified, it defaults to the
              value given for nr.  Values in the range 9 to 15 may be used for
              nr  and  nt;  larger  values give better compression but consume
              more kernel memory for compression dictionaries.  Alternatively,
              a  value  of  0  for  nr  or  nt  disables  compression  in  the
              corresponding direction.  Use nobsdcomp or bsdcomp 0 to  disable
              BSD-Compress compression entirely.

       cdtrcts
              Use  a  non-standard  hardware  flow  control  (i.e. DTR/CTS) to
              control the flow of data on the serial  port.   If  neither  the
              crtscts,  the nocrtscts, the cdtrcts nor the nocdtrcts option is
              given, the hardware flow control setting for the serial port  is
              left  unchanged.   Some  serial  ports (such as Macintosh serial
              ports) lack a true RTS output. Such serial ports use  this  mode
              to  implement true bi-directional flow control. The sacrifice is
              that this flow control mode does not permit using DTR as a modem
              control line.

       chap-interval n
               如果有给这个选项,pppd将会每n 秒重新盘查彼端。

       chap-max-challenge n
               将CHAP盘查(challenge)传输的最大数目设为n(预 设为10)。

       chap-restart n
               将CHAP重新开始的间隔(重新传输的时间限制)设为n
              秒钟(预设为3)。

       connect-delay n
              Wait for up n milliseconds after the connect script finishes for
              a  valid  PPP packet from the peer.  At the end of this time, or
              when a valid PPP packet is received from  the  peer,  pppd  will
              commence  negotiation  by  sending  its  first  LCP packet.  The
              default value is 1000 (1 second).  This wait period only applies
              if the connect or pty option is used.

       debug  递增侦错层级(与-d相同)。如果加上这个选项,pppd
              将以可供阅读的格式记录所有传送或接收的控制封包内容。
              这些封包透过syslog以facilitydaemon还有level
              debug加以记录。该资讯可以适当设定/etc/syslog.conf
              来导向到一个档案去。(参阅syslog.conf(5))。(如果
              pppd以开启扩充侦错(extradebugging)编译的话,它将
              会使用facilitylocal2取代daemon来记录讯息)。

       default-asyncmap
              Disable  asyncmap negotiation, forcing all control characters to
              be escaped for both the transmit and the receive direction.

       default-mru
              Disable MRU  [Maximum  Receive  Unit]  negotiation.   With  this
              option,  pppd  will  use the default MRU value of 1500 bytes for
              both the transmit and receive direction.

       deflate nr,nt
              Request that the peer compress packets that it sends, using  the
              Deflate  scheme,  with a maximum window size of 2**nr bytes, and
              agree to compress packets sent to the peer with a maximum window
              size of 2**nt bytes.  If nt is not specified, it defaults to the
              value given for nr.  Values in the range 9 to 15 may be used for
              nr  and  nt;  larger  values give better compression but consume
              more kernel memory for compression dictionaries.  Alternatively,
              a  value  of  0  for  nr  or  nt  disables  compression  in  the
              corresponding direction.  Use nodeflate or deflate 0 to  disable
              Deflate  compression  entirely.   (Note:  pppd  requests Deflate
              compression in preference to BSD-Compress if  the  peer  can  do
              either.)

       demand Initiate  the  link  only  on  demand, i.e. when data traffic is
              present.  With this  option,  the  remote  IP  address  must  be
              specified by the user on the command line or in an options file.
              Pppd will initially configure the interface and enable it for IP
              traffic  without  connecting  to  the  peer.   When  traffic  is
              available,  pppd  will  connect  to   the   peer   and   perform
              negotiation,  authentication, etc.  When this is completed, pppd
              will commence passing data packets (i.e., IP packets) across the
              link.

              The demand option implies the persist option.  If this behaviour
              is not desired,  use  the  nopersist  option  after  the  demand
              option.   The  idle  and  holdoff  options  are  also  useful in
              conjuction with the demand option.

       domain d
               新增领域名称到本地主机名称以支援验证。例如,如
              果gethostname()回应porsche这个名称,但是完整合
              格的领域名称是porsche.Quotron.COM的话,你可以使用
              domain选项来将领域名称设为Quotron.COM。
               Pppd would then use the name porsche.Quotron.COM for looking up
              secrets in the secrets file, and as the default name to send  to
              the peer when authenticating itself to the peer.  This option is
              privileged.

       dryrun With the dryrun option, pppd  will  print  out  all  the  option
              values  which  have  been  set  and then exit, after parsing the
              command line and options files and checking the  option  values,
              but before initiating the link.  The option values are logged at
              level info, and also  printed  to  standard  output  unless  the
              device on standard output is the device that pppd would be using
              to communicate with the peer.

       dump   With the dump option, pppd will print out all the option  values
              which  have  been  set.   This  option is like the dryrun option
              except that pppd proceeds as normal rather than exiting.

       endpoint <epdisc>
              Sets the endpoint discriminator sent by the local machine to the
              peer  during  multilink negotiation to <epdisc>.  The default is
              to use the MAC address of the first ethernet  interface  on  the
              system,  if any, otherwise the IPv4 address corresponding to the
              hostname, if any,  provided  it  is  not  in  the  multicast  or
              locally-assigned  IP  address  ranges, or the localhost address.
              The endpoint discriminator can be the string null or of the form
              type:value, where type is a decimal number or one of the strings
              local, IP, MAC, magic, or phone.  The value is an IP address  in
              dotted-decimal notation for the IP type, or a string of bytes in
              hexadecimal, separated by periods or colons for the other types.
              For  the MAC type, the value may also be the name of an ethernet
              or similar network interface.  This  option  is  currently  only
              available under Linux.

       hide-password
              When  logging  the  contents  of PAP packets, this option causes
              pppd to exclude the password string from the log.  This  is  the
              default.

       holdoff n
              Specifies how many seconds to wait before re-initiating the link
              after it terminates.  This option only has  any  effect  if  the
              persist  or  demand  option  is used.  The holdoff period is not
              applied if the link was terminated because it was idle.

       idle n Specifies that pppd should disconnect if the link is idle for  n
              seconds.   The  link  is  idle  when  no  data  packets (i.e. IP
              packets) are being sent or received.  Note: it is not  advisable
              to  use  this  option with the persist option without the demand
              option.  If the active-filter  option  is  given,  data  packets
              which  are  rejected by the specified activity filter also count
              as the link being idle.

       ipcp-accept-local
              加上这个选项的话,pppd将会接受彼端对於本地IP位址
              的意见,即使本地的IP位址已驹谀掣鲅∠钪兄付ā

       ipcp-accept-remote
              加上这个选项的话,pppd将会接受彼端对於它的IP位址
              的意见,即使远端的IP位址已驹谀掣鲅∠钪兄付ā

       ipcp-max-configure n
               将IPCP配置要求(configure-request)传输的最大数目设
              为n(预设为10)。

       ipcp-max-failure n
              将开始传送配置拒绝(configure-Rejects)之前的IPCP配
              置未接收(configure-NAKs)的最大数目以取代n(预设 为10)。

       ipcp-max-terminate n
               将IPCP终结要求(terminate-request)传输的最大数目设            为
              n(预设为3)。

       ipcp-restart n
               将IPCP重新开始的间隔(重新传输的时间限制)设为n
              秒钟(预设为3)。

       ipparam string
              Provides an extra parameter to the ip-up  and  ip-down  scripts.
              If this option is given, the string supplied is given as the 6th
              parameter to those scripts.

       ipv6cp-max-configure n
              Set the maximum number of IPv6CP configure-request transmissions
              to n (default 10).

       ipv6cp-max-failure n
              Set  the maximum number of IPv6CP configure-NAKs returned before
              starting to send configure-Rejects instead to n (default 10).

       ipv6cp-max-terminate n
              Set the maximum number of IPv6CP terminate-request transmissions
              to n (default 3).

       ipv6cp-restart n
              Set  the  IPv6CP  restart interval (retransmission timeout) to n
              seconds (default 3).

       ipx    Enable the IPXCP and IPX protocols.  This  option  is  presently
              only  supported  under  Linux,  and only if your kernel has been
              configured to include IPX support.

       ipx-network n
              Set the IPX network number in the IPXCP configure request  frame
              to  n, a hexadecimal number (without a leading 0x).  There is no
              valid default.  If this option is  not  specified,  the  network
              number is obtained from the peer.  If the peer does not have the
              network number, the IPX protocol will not be started.

       ipx-node n:m
              Set the IPX node numbers. The two  node  numbers  are  separated
              from  each  other  with a colon character. The first number n is
              the local node number. The second number m is  the  peer's  node
              number.  Each  node  number  is a hexadecimal number, at most 10
              digits long. The node numbers on the ipx-network must be unique.
              There  is no valid default. If this option is not specified then
              the node numbers are obtained from the peer.

       ipx-router-name <string>
              Set the name of the router. This is a string and is sent to  the
              peer as information data.

       ipx-routing n
              Set  the  routing  protocol  to be received by this option. More
              than one instance of ipx-routing may be  specified.  The  'none'
              option (0) may be specified as the only instance of ipx-routing.
              The values may be 0 for NONE, 2 for RIP/SAP, and 4 for NLSP.

       ipxcp-accept-local
              Accept the peer's NAK for the node number specified in the  ipx-
              node  option.  If a node number was specified, and non-zero, the
              default is to insist that the value be used. If you include this
              option  then  you  will permit the peer to override the entry of
              the node number.

       ipxcp-accept-network
              Accept the peer's NAK for the network number  specified  in  the
              ipx-network  option. If a network number was specified, and non-
              zero, the default is to insist that the value be  used.  If  you
              include  this  option  then you will permit the peer to override
              the entry of the node number.

       ipxcp-accept-remote
              Use the peer's network number specified in the configure request
              frame.  If  a  node  number  was specified for the peer and this
              option was not specified, the peer will be  forced  to  use  the
              value which you have specified.

       ipxcp-max-configure n
              Set  the  maximum number of IPXCP configure request frames which
              the system will send to n. The default is 10.

       ipxcp-max-failure n
              Set the maximum number of  IPXCP  NAK  frames  which  the  local
              system  will  send  before  it  rejects the options. The default
              value is 3.

       ipxcp-max-terminate n
              Set the maximum nuber of IPXCP terminate request  frames  before
              the  local  system  considers  that the peer is not listening to
              them. The default value is 3.

       kdebug n
              开启核心层级中的PPP驱动程式侦错码。The argument values depend on
              the  specific  kernel  driver,  but in general a value of 1 will
              enable general kernel debug messages.  (Note that these messages
              are usually only useful for debugging the kernel driver itself.)
              For    the    Linux    2.2.x    kernel    driver,    参数n是一个
              由下列值所组合的数字:1开启一般侦错讯息,2要求印
              出所接收到的封包内容,而4要求印出传输的封包内容。    On     most
              systems,  messages printed by the kernel are logged by syslog(1)
              to a file as  directed  in  the  /etc/syslog.conf  configuration
              file.

       ktune  Enables  pppd  to  alter  kernel settings as appropriate.  Under
              Linux,   pppd   will   enable   IP    forwarding    (i.e.    set
              /proc/sys/net/ipv4/ip_forward  to  1)  if the proxyarp option is
              used, and will enable the dynamic IP address  option  (i.e.  set
              /proc/sys/net/ipv4/ip_dynaddr  to 1) in demand mode if the local
              address changes.

       lcp-echo-failure n
               如果有给这个选项,那麽如果传送n个LCP回应要求没
              有接收到有效的LCP回应回覆的话pppd将会推测彼端是
              死掉的。如果发生这种情形,pppd将会终结该连线。这个
              选项的使用要求一个非零的lcp-echo-interval参数值。
              这个选项可以用在硬体数据机控制线路无法使用的情况下
              当实际连线被中断之後(e.g.,数据机已竟叶希┲战 pppd的执行。

       lcp-echo-interval n
              如果有给这个选项,pppd每秒将会送出一个LCP回         应要求(echo-
              request)封包(frame)给彼端。在Linux系
              统下,回应要求在n秒内没有从彼端接收到封包时会被送
              出。一般彼端应该以传送一个回应回覆(echo-reply)来反
              应该回应要求。这个选项可以与lcp-echo-failure选项
              一起使用来侦测不再连线的彼端。

       lcp-max-configure n
               将LCP配置要求(configure-request)传输的最大数目设
              为n(预设为10)。

       lcp-max-failure n
               将开始传送配置拒绝(configure-Rejects)之前的LCP配
              置未接收(configure-NAKs)的最大数目设置为n(预设 为10)。

       lcp-max-terminate n
               将LCP终结要求(terminate-request)传输的最大数目设
              为n(预设为3)。

       lcp-restart n
              将LCP重新开始的间隔(重新传输的时间限制)设为 秒钟(预设为3)。

       linkname name
              Sets  the  logical name of the link to name.  Pppd will create a
              file  named  ppp-name.pid  in  /var/run  (or  /etc/ppp  on  some
              systems)  containing  its  process  ID.   This  can be useful in
              determining which instance of pppd is responsible for  the  link
              to a given peer system.  This is a privileged option.

       local  不要使用数据机控制线路。  With this option, pppd will ignore the
              state of the CD (Carrier Detect) signal from the modem and  will
              not change the state of the DTR (Data Terminal Ready) signal.

       logfd n
              Send  log  messages  to  file  descriptor n.  Pppd will send log
              messages to at most one file or  file  descriptor  (as  well  as
              sending  the  log  messages  to  syslog), so this option and the
              logfile option are mutually exclusive.  The default is for  pppd
              to  send  log messages to stdout (file descriptor 1), unless the
              serial port is already open on stdout.

       logfile filename
              Append log messages to the file filename (as well as sending the
              log messages to syslog).  The file is opened with the privileges
              of the user who invoked pppd, in append mode.

       login  使用系统密码资料库验证使用PAP的彼端。 and record the user in the
              system  wtmp file.  Note that the peer must have an entry in the
              /etc/ppp/pap-secrets  file  as  well  as  the  system   password
              database to be allowed access.

       maxconnect n
              Terminate  the connection when it has been available for network
              traffic for n seconds (i.e. n seconds after  the  first  network
              control protocol comes up).

       maxfail n
              Terminate  after  n  consecutive  failed connection attempts.  A
              value of 0 means no limit.  The default value is 10.

       modem  使用数据机控制线路。This  option  is  the  default.   With  this
              option,  pppd  will wait for the CD (Carrier Detect) signal from
              the modem to be asserted when opening the serial device  (unless
              a  connect  script is specified), and it will drop the DTR (Data
              Terminal Ready) signal briefly when the connection is terminated
              and      before      executing      the      connect     script.
              在Ultrix上,这个选项会实作硬 体流量控制,像crtsct选项作的。

       mp     Enables the use of PPP multilink;  this  is  an  alias  for  the
              `multilink'  option.   This  option  is currently only available
              under Linux.

       mpshortseq
              Enables the use of short (12-bit) sequence numbers in  multilink
              headers,  as opposed to 24-bit sequence numbers.  This option is
              only available under Linux, and only has any effect if multilink
              is enabled (see the multilink option).

       mrru n Sets  the  Maximum Reconstructed Receive Unit to n.  The MRRU is
              the maximum size for a received packet on  a  multilink  bundle,
              and  is  analogous  to  the  MRU for the individual links.  This
              option is currently only available under Linux, and only has any
              effect if multilink is enabled (see the multilink option).

       ms-dns <addr>
              If  pppd  is  acting  as a server for Microsoft Windows clients,
              this option allows pppd to supply one or two  DNS  (Domain  Name
              Server)  addresses  to  the clients.  The first instance of this
              option specifies the primary DNS address;  the  second  instance
              (if  given)  specifies  the secondary DNS address.  (This option
              was present in some older versions of pppd under the  name  dns-
              addr.)

       ms-wins <addr>
              If  pppd  is acting as a server for Microsoft Windows or "Samba"
              clients, this option allows pppd  to  supply  one  or  two  WINS
              (Windows   Internet  Name  Services)  server  addresses  to  the
              clients.  The  first  instance  of  this  option  specifies  the
              primary  WINS  address; the second instance (if given) specifies
              the secondary WINS address.

       multilink
              Enables the use of the PPP multilink protocol.  If the peer also
              supports  multilink,  then this link can become part of a bundle
              between the local system and the peer.  If there is an  existing
              bundle  to  the  peer,  pppd will join this link to that bundle,
              otherwise pppd will create a  new  bundle.   See  the  MULTILINK
              section  below.   This  option is currently only available under
              Linux.

       name name
              将本地系统的名称设为用来进行验证。 This is a privileged  option.
              With this option, pppd will use lines in the secrets files which
              have name as the second field when looking for a secret  to  use
              in authenticating the peer.  In addition, unless overridden with
              the user option, name will be used as the name to  send  to  the
              peer  when  authenticating  the local system to the peer.  (Note
              that pppd does not append the domain name to name.)

       netmask n
               把该界面网路掩码设为,这是一个以″十进位数值加
              小数点″("decimaldot")符号表示的32位元网路掩码
              (e.g.255.255.255.0)。If  this  option  is   given,   the   value
              specified is ORed with the default netmask.  The default netmask
              is chosen based on the negotiated remote IP address; it  is  the
              appropriate network mask for the class of the remote IP address,
              ORed with  the  netmasks  for  any  non  point-to-point  network
              interfaces  in the system which are on the same network.  (Note:
              on some platforms, pppd will always use 255.255.255.255 for  the
              netmask,  if  that is the only appropriate value for a point-to-
              point interface.)

       noaccomp
              Disable Address/Control compression in both directions (send and
              receive).

       noauth Do  not require the peer to authenticate itself.  This option is
              privileged.

       nobsdcomp
              Disables BSD-Compress compression;  pppd  will  not  request  or
              agree to compress packets using the BSD-Compress scheme.

       noccp  Disable  CCP  (Compression  Control Protocol) negotiation.  This
              option should only be required if the peer  is  buggy  and  gets
              confused by requests from pppd for CCP negotiation.

       nocrtscts
              Disable hardware flow control (i.e. RTS/CTS) on the serial port.
              If neither the crtscts nor the nocrtscts nor the cdtrcts nor the
              nocdtrcts option is given, the hardware flow control setting for
              the serial port is left unchanged.

       nocdtrcts
              This option is a synonym for nocrtscts. Either of these  options
              will disable both forms of hardware flow control.

       nodefaultroute
              Disable  the  defaultroute option.  The system administrator who
              wishes to prevent users from creating default routes  with  pppd
              can do so by placing this option in the /etc/ppp/options file.

       nodeflate
              Disables  Deflate compression; pppd will not request or agree to
              compress packets using the Deflate scheme.

       nodetach
              Don't  detach  from  the  controlling  terminal.   Without  this
              option,  if  a  serial  device  other  than  the terminal on the
              standard  input  is  specified,  pppd  will  fork  to  become  a
              background process.

       noendpoint
              Disables pppd from sending an endpoint discriminator to the peer
              or accepting one  from  the  peer  (see  the  MULTILINK  section
              below).   This  option  should  only  be required if the peer is
              buggy.

       noip   Disable IPCP negotiation  and  IP  communication.   This  option
              should  only  be required if the peer is buggy and gets confused
              by requests from pppd for IPCP negotiation.

       noipv6 Disable IPv6CP negotiation and IPv6 communication.  This  option
              should  only  be required if the peer is buggy and gets confused
              by requests from pppd for IPv6CP negotiation.

       noipdefault
              关闭在没有指定本地IP位址时所进行的预设动作,这是
              用来由从主机名称决定(如果可能的话)决定本地IP位
              址。加上这个选项的话,彼端将必须在进行IPCP猩淌
              (除非在指令列或在选项档中明确地指定它)提供本地的 IP位址。

       noipx  Disable the IPXCP and IPX protocols.  This option should only be
              required if the peer is buggy and gets confused by requests from
              pppd for IPXCP negotiation.

       noktune
              Opposite of the ktune option; disables pppd from changing system
              settings.

       nolog  Do not send log messages to a file  or  file  descriptor.   This
              option cancels the logfd and logfile options.

       nomagic
              Disable magic number negotiation.  With this option, pppd cannot
              detect a looped-back line.  This option should only be needed if
              the peer is buggy.

       nomp   Disables  the  use  of  PPP multilink.  This option is currently
              only available under Linux.

       nompshortseq
              Disables the use of short (12-bit) sequence numbers in  the  PPP
              multilink  protocol, forcing the use of 24-bit sequence numbers.
              This option is currently only available under  Linux,  and  only
              has any effect if multilink is enabled.

       nomultilink
              Disables  the  use  of  PPP multilink.  This option is currently
              only available under Linux.

       nopcomp
              Disable protocol  field  compression  negotiation  in  both  the
              receive and the transmit direction.

       nopersist
              Exit  once  a  connection has been made and terminated.  This is
              the default  unless  the  persist  or  demand  option  has  been
              specified.

       nopredictor1
              Do not accept or agree to Predictor-1 compression.

       noproxyarp
              Disable  the  proxyarp  option.   The  system  administrator who
              wishes to prevent users from creating  proxy  ARP  entries  with
              pppd  can  do  so by placing this option in the /etc/ppp/options
              file.

       notty  Normally, pppd requires a terminal device.   With  this  option,
              pppd will allocate itself a pseudo-tty master/slave pair and use
              the slave as its terminal device.   Pppd  will  create  a  child
              process  to  act  as  a `character shunt' to transfer characters
              between the pseudo-tty master and its standard input and output.
              Thus  pppd  will  transmit characters on its standard output and
              receive characters on its standard input even if  they  are  not
              terminal  devices.   This  option  increases the latency and CPU
              overhead of transferring data over the ppp interface as  all  of
              the characters sent and received must flow through the character
              shunt process.  An explicit device name may not be given if this
              option is used.

       novj   Disable Van Jacobson style TCP/IP header compression in both the
              transmit and the receive direction.

       novjccomp
              Disable the connection-ID compression  option  in  Van  Jacobson
              style  TCP/IP  header  compression.  With this option, pppd will
              not omit the connection-ID byte  from  Van  Jacobson  compressed
              TCP/IP headers, nor ask the peer to do so.

       papcrypt
              Indicates  that  all  secrets  in  the /etc/ppp/pap-secrets file
              which are used  for  checking  the  identity  of  the  peer  are
              encrypted,  and  thus  pppd  should not accept a password which,
              before  encryption,  is  identical  to  the  secret   from   the
              /etc/ppp/pap-secrets file.

       pap-max-authreq n
               将PAP验证要求(authenticate-request)传输的最大数目
              设为n(预设为10)。

       pap-restart n
               将PAP重新开始的间隔(重新传输的时间限制)设为n
              秒钟(预设为3)。

       pap-timeout n
              Set  the  maximum  time  that  pppd  will  wait  for the peer to
              authenticate itself with PAP to n seconds (0 means no limit).

       pass-filter filter-expression
              Specifies a packet filter to applied to data packets being  sent
              or  received  to  determine  which  packets should be allowed to
              pass.  Packets which are rejected by  the  filter  are  silently
              discarded.   This option can be used to prevent specific network
              daemons (such as routed) using up link bandwidth, or to  provide
              a basic firewall capability.  The filter-expression syntax is as
              described for  tcpdump(1),  except  that  qualifiers  which  are
              inappropriate  for  a  PPP  link, such as ether and arp, are not
              permitted.  Generally the filter expression should  be  enclosed
              in  single-quotes  to  prevent whitespace in the expression from
              being interpreted by the shell.  Note that  it  is  possible  to
              apply  different  constraints  to  incoming and outgoing packets
              using the  inbound  and  outbound  qualifiers.  This  option  is
              currently only available under NetBSD, and then only if both the
              kernel and pppd were compiled with PPP_FILTER defined.

       persist
              Do not exit after a connection is  terminated;  instead  try  to
              reopen the connection.

       plugin filename
              Load  the shared library object file filename as a plugin.  This
              is a privileged option.

       predictor1
              Request that the  peer  compress  frames  that  it  sends  using
              Predictor-1  compression,  and  agree  to  compress  transmitted
              frames with Predictor-1 if requested.  This option has no effect
              unless the kernel driver supports Predictor-1 compression.

       privgroup group-name
              Allows  members  of  group group-name to use privileged options.
              This is a privileged option.  Use of this option  requires  care
              as  there  is no guarantee that members of group-name cannot use
              pppd to become  root  themselves.   Consider  it  equivalent  to
              putting the members of group-name in the kmem or disk group.

       proxyarp
              以彼端的IP位址以及该系统的乙太网路位址增加一个项
              目到系统的ARP[AddressResolutionProtocol位址解 译卸╙表格。  This
              will  have the effect of making the peer appear to other systems
              to be on the local ethernet.

       pty script
              Specifies that the command script is to be used  to  communicate
              rather  than  a  specific  terminal  device.  Pppd will allocate
              itself a pseudo-tty master/slave pair and use the slave  as  its
              terminal device.  The script will be run in a child process with
              the pseudo-tty master as its  standard  input  and  output.   An
              explicit  device  name  may not be given if this option is used.
              (Note: if the record option is used in conjuction with  the  pty
              option,  the child process will have pipes on its standard input
              and output.)

       receive-all
              With this option, pppd will accept all control  characters  from
              the  peer,  including  those  marked  in  the  receive asyncmap.
              Without this option,  pppd  will  discard  those  characters  as
              specified  in RFC1662.  This option should only be needed if the
              peer is buggy.

       record filename
              Specifies that  pppd  should  record  all  characters  sent  and
              received  to  a  file  named  filename.   This file is opened in
              append mode, using the user's  user-ID  and  permissions.   This
              option  is  implemented  using  a  pseudo-tty  and  a process to
              transfer characters between the pseudo-tty and the  real  serial
              device,  so  it  will  increase  the latency and CPU overhead of
              transferring data over the ppp interface.   The  characters  are
              stored  in  a  tagged  format  with  timestamps,  which  can  be
              displayed in readable form using the pppdump(8) program.

       remotename name
              将远端系统的假设名称设为以进行验证。

       refuse-chap
              With this option, pppd will not agree to authenticate itself  to
              the peer using CHAP.

       refuse-pap
              With  this option, pppd will not agree to authenticate itself to
              the peer using PAP.

       require-chap
              Require the peer to authenticate itself  using  CHAP  [Challenge
              Handshake Authentication Protocol] authentication.

       require-pap
              Require  the  peer  to  authenticate  itself using PAP [Password
              Authentication Protocol] authentication.

       show-password
              When logging the contents of PAP  packets,  this  option  causes
              pppd to show the password string in the log message.

       silent 加上这个选项,pppd将不会传输LCP封包来初使一个连
              线一直到从彼端接收到一个有效的LCP封包。(就像是给
              旧版pppd使用的"passive"选项)。

       sync   Use  synchronous  HDLC  serial encoding instead of asynchronous.
              The device used by pppd with this option must have sync support.
              Currently  supports  Microgate SyncLink adapters under Linux and
              FreeBSD 2.2.8 and later.

       updetach
              With this option, pppd will detach from its controlling terminal
              once  it has successfully established the ppp connection (to the
              point where the first network control protocol, usually  the  IP
              control protocol, has come up).

       usehostname
              强迫主机名称使用本地系统的名称来进行验证。(这会盖过name选项)。
              This option is not normally needed  since  the  name  option  is
              privileged.

       usepeerdns
              Ask  the  peer  for up to 2 DNS server addresses.  The addresses
              supplied by the peer (if any) are passed to  the  /etc/ppp/ip-up
              script in the environment variables DNS1 and DNS2.  In addition,
              pppd will create an /etc/ppp/resolv.conf file containing one  or
              two  nameserver lines with the address(es) supplied by the peer.

       user name
              将使用者名称设为以便让使用PAP的彼端验证这台机器时使用。

       vj-max-slots n
              Sets the number of connection  slots  to  be  used  by  the  Van
              Jacobson  TCP/IP header compression and decompression code to n,
              which must be between 2 and 16 (inclusive).

       welcome script
              Run the executable or shell command specified by  script  before
              initiating  PPP  negotiation,  after the connect script (if any)
              has completed.  A value for this option from a privileged source
              cannot be overridden by a non-privileged user.

       xonxoff
              使用软体流量控制(i.e.XON/XOFF)来控制串列埠上的资料流。

 OPTIONS FILES
       选项可以从档案取出使用就如同使用命令列一般。pppd在查看指
       令列之前先从档案/etc/ppp/options以及~/.ppprc读取选项。 ttyname (in that
       order)  before  processing  the options on the command line.  (In fact,
       the command-line options are scanned to find the terminal  name  before
       the  options.ttyname  file  is  read.)   In  forming  the  name  of the
       options.ttyname file, the initial /dev/ is removed  from  the  terminal
       name, and any remaining / characters are replaced with dots.

       一个选项档案以空白字元为界被剖析成一串单字。空白字元可以用
       双引号(")包括在一个单字里。倒斜线引用其後的字元。而hash
       (#)符号开始一段注解持续到该行结束。  There  is  no restriction on using
       the file or call options within an options file.

 SECURITY
       pppd                提供系统管理人员充份的存取控制能力这表示以PPP存取一
       台伺服机器可以提供给合法的使用者使用而不必担心危及该伺服器
       或所在网路的安全性。这有一部份是以/etc/ppp/options档案来
       提供,在这里系统管理人员可以放置在执行pppd的时候用来要求
       验证的选项,而部份是由PAP以及CHAP暗号档案来提供,其中
       系统管理人员可以限制个别的使用者可以使用的一群IP位址。

       The  default  behaviour  of pppd is to allow an unauthenticated peer to
       use a given IP address only if the system does not already have a route
       to  that IP address.  For example, a system with a permanent connection
       to the wider internet will normally have a default route, and thus  all
       peers  will  have  to  authenticate  themselves  in  order  to set up a
       connection.  On such a system, the auth option is the default.  On  the
       other  hand,  a system where the PPP link is the only connection to the
       internet will not normally have a default route, so the  peer  will  be
       able to use almost any IP address without authenticating itself.

       As  indicated  above,  some  security-sensitive options are privileged,
       which means that they may not be used  by  an  ordinary  non-privileged
       user  running  a  setuid-root  pppd, either on the command line, in the
       user's ~/.ppprc file, or in an options file read using the file option.
       Privileged  options  may  be  used  in  /etc/ppp/options  file or in an
       options file read using the call option.  If pppd is being run  by  the
       root user, privileged options can be used without restriction.

       When  opening  the device, pppd uses either the invoking user's user ID
       or the root UID (that is, 0), depending on whether the device name  was
       specified  by the user or the system administrator.  If the device name
       comes from a privileged source, that is, /etc/ppp/options or an options
       file  read  using  the call option, pppd uses full root privileges when
       opening the device.   Thus,  by  creating  an  appropriate  file  under
       /etc/ppp/peers, the system administrator can allow users to establish a
       ppp connection  via  a  device  which  they  would  not  normally  have
       permission to access.  Otherwise pppd uses the invoking user's real UID
       when opening the device.

AUTHENTICATION

       Authentication is the process whereby one peer convinces the  other  of
       its  identity.   This  involves  the first peer sending its name to the
       other, together with some kind of secret information which  could  only
       come  from  the  genuine  authorized  user  of  that  name.  In such an
       exchange, we will call the first peer the "client" and  the  other  the
       "server".   The  client has a name by which it identifies itself to the
       server, and the server also has a name by which it identifies itself to
       the  client.   Generally  the  genuine  client  shares  some secret (or
       password) with the server, and authenticates itself by proving that  it
       knows  that  secret.   Very  often,  the  names used for authentication
       correspond to the internet hostnames of the  peers,  but  this  is  not
       essential.

       At  present,  pppd  supports two authentication protocols: the Password
       Authentication   Protocol   (PAP)   and   the    Challenge    Handshake
       Authentication  Protocol  (CHAP).   PAP involves the client sending its
       name and a cleartext password to the server to authenticate itself.  In
       contrast,  the  server  initiates  the  CHAP authentication exchange by
       sending a challenge to the client (the challenge  packet  includes  the
       server's name).  The client must respond with a response which includes
       its name plus a hash value derived  from  the  shared  secret  and  the
       challenge, in order to prove that it knows the secret.

       The  PPP  protocol, being symmetrical, allows both peers to require the
       other  to  authenticate  itself.   In  that  case,  two  separate   and
       independent  authentication  exchanges  will  occur.  The two exchanges
       could  use  different  authentication  protocols,  and  in   principle,
       different names could be used in the two exchanges.

        pppd预设的动作是如果有要求就同意进行验证,并且不要求从彼
       端做验证。然而如果没有可以用来验证的暗号则pppd将不会同意     以特殊的-
       定来验证它自己。

        验证的基础是由暗号档案选择的暗号(/etc/ppp/pap-secrets是
       给PAP使用的,/etc/ppp/chap-secrets则是给CHAP使用)。
       这两个暗号档案都具有相同的格式,而且两者都可以储放暗号给数
       种伺服器(验证彼端)及客户(被验证端)组合使用。注意pppd
       可以最为伺服端以及客户端,而且如果需要的话两方可以使用不同 的卸ā

        一个暗号档案如同选项档案一般被剖析成单字。一个暗号是由最少
       包含3个单字的一行所指定,依序是客户,伺服器,暗号。在同
       一行中任何跟在其後的单字都被当作是给客户的可接受IP位址列
       表。如果该行只有3个单字,这假设任何IP位址都可以;不允
       许所有的IP位址的话,使用"-"。如果暗号是以'@'开始,其
       後所接的单字将被假设为可以从中读取暗号的档案名称。而以一个
       "*"字元作为客户或伺服端的名称会符合任何名称。在选择一个暗
       号时,pppd会选择最符合的,i.e.最少万用字元的那个。

       如此一个暗号档案包含用来验证其它主机,以及用来为其它主机验
       证自己两者的暗号。选择使用哪个暗号是根据该主机(本地名称)
       以及其彼端(远端名称)而定。本地名称的设定如下:

       If the secret starts with an `@', what follows is  assumed  to  be  the
       name  of  a file from which to read the secret.  A "*" as the client or
       server name matches any name.  When selecting a secret, pppd takes  the
       best match, i.e.  the match with the fewest wildcards.

       Any  following  words  on  the  same  line  are  taken  to be a list of
       acceptable IP addresses for that client.  If there are only 3 words  on
       the  line,  or  if  the  first  word  is "-", then all IP addresses are
       disallowed.  To allow any address, use "*".  A word starting  with  "!"
       indicates that the specified address is not acceptable.  An address may
       be followed by "/" and a number n, to indicate a whole subnet, i.e. all
       addresses which have the same value in the most significant n bits.  In
       this form, the address may be followed by a plus sign ("+") to indicate
       that  one  address  from  the  subnet  is  authorized, based on the ppp
       network interface unit number in use.  In this case, the host  part  of
       the address will be set to the unit number plus one.

       Thus  a  secrets  file  contains both secrets for use in authenticating
       other hosts, plus secrets which we use for authenticating ourselves  to
       others.   When  pppd  is  authenticating  the peer (checking the peer's
       identity), it chooses a secret with the peer's name in the first  field
       and  the name of the local system in the second field.  The name of the
       local system defaults to the hostname, with the domain name appended if
       the  domain  option  is  used.  This default can be overridden with the
       name option, except when the usehostname option is used.

       When pppd is choosing a secret to use in authenticating itself  to  the
       peer,  it  first  determines  what  name it is going to use to identify
       itself to the peer.  This name can be specified by the  user  with  the
       user option.  If this option is not used, the name defaults to the name
       of the local system, determined as described in the previous paragraph.
       Then  pppd looks for a secret with this name in the first field and the
       peer's name in the second field.  Pppd will know the name of  the  peer
       if  CHAP  authentication is being used, because the peer will have sent
       it in the challenge packet.  However, if PAP is being used,  pppd  will
       have  to  determine  the  peer's name from the options specified by the
       user.   The  user  can  specify  the  peer's  name  directly  with  the
       remotename  option.   Otherwise, if the remote IP address was specified
       by a name (rather than in numeric form), that name will be used as  the
       peer's name.  Failing that, pppd will use the null string as the peer's
       name.

        当以PAP验证彼端时,一个""暗号符合任何由彼端所提供密码。
       如果密码不符合暗号,密码被以crypt()编码并且再次检查暗号;
       因此验证彼端的暗号可以编码方式储放。

       如果指定有login选项,
       使用者名称以及密码也会被以系统的密码资料库检查。因此系统管
       理人员可以设定pap-secrets档案以便只允许某些使用者以PPP
       连线,并且限制每个使用者可以使用一些IP位址。  Typically, when using the
       login option, the secret in /etc/ppp/pap-secrets  would  be  "",  which
       will  match any password supplied by the peer.  This avoids the need to
       have the same secret in two places.

        验证必须在IPCP(或任何其它网路控制卸ǎ┛贾氨煌耆
       满足。如果验证失败,pppd将会终结连线(关闭LCP)。如果            IPCP-
       商出一个无法接受的远端主机IP位址,IPCP将会关闭。
       IP封包只有在IPCP打开的时候才能传送或接收。

        即使本地主机一般会要求验证,在某些案例中会希望允一些无法验
       证它们自己的主机连线并使用所限制的IP位址其中之一。如果彼
       在被要求时拒绝验证它自己,pppd将会把它当成等於是在使用者
       名称以及密码上使用空字串来以PAP验证。所以,藉由增加一行
       指定空字串为客户以及密码到pap-secrets档案去,允许拒绝验
       证自己的主机进行有限制的存取是可能的。

 ROUTING
        当IPCP猩坛晒Φ赝瓿墒保琾ppd将会通知核心该ppp界面本地
       以及远端的IP位址。这足够用来建立一个主机到该连线远端的递
       送路径,该路径将使两端能交换IP封包。与其它的机器进行通讯
       往往需要更进一步地修改递送表格(routingtables)以及/或是 ARP(位址解译-
       定)表格。在某些案例中这将透过routed或是
       gated隐形程式的动作自动地完成,但是在大部分的案例中需要更
       进一步的介入。

        有时候会希望透过远端主机来增加一个预设递送路径,像是在一台
       只透过ppp界面连线到Internet的机器。此defaultroute选
       项使得pppd在IPCP完成时建立起这麽一个预设的递送路径,并
       且在该线路被终结时将之删除。

        在某些情况下会希望使用proxyARP,例如在一台连结到区域网
       路的伺服机器上,为了能够允许其它的主机与远端主机进行通讯。
       proxyarp选项引发pppd去寻找一个与远端主机在相同子网路上
       的网路界面(一个支援广播(boardcast)以及ARP的界面,不但要
       是可用的并且不是一个点对点或回授界面)。如果找到,pppd会
       以该远端主机的IP位址以及所找到的网路界面之硬体位址建立一
       个永久的,公开的ARP项目。

       When the demand option is used, the interface IP addresses have already
       been set at the point when IPCP comes up.  If pppd has not been able to
       negotiate  the  same  addresses that it used to configure the interface
       (for example when the peer is an  ISP  that  uses  dynamic  IP  address
       assignment),  pppd  has  to  change  the  interface IP addresses to the
       negotiated addresses.  This may disrupt existing connections,  and  the
       use of demand dialling with peers that do dynamic IP address assignment
       is not recommended.

MULTILINK

       Multilink PPP provides the capability to combine two or more PPP  links
       between  a  pair of machines into a single `bundle', which appears as a
       single virtual PPP  link  which  has  the  combined  bandwidth  of  the
       individual  links.   Currently,  multilink  PPP is only supported under
       Linux.

       Pppd detects that the link it is controlling is connected to  the  same
       peer  as  another  link using the peer's endpoint discriminator and the
       authenticated identity of the peer (if it authenticates  itself).   The
       endpoint discriminator is a block of data which is hopefully unique for
       each peer.  Several types of  data  can  be  used,  including  locally-
       assigned  strings  of  bytes,  IP  addresses,  MAC  addresses, randomly
       strings of bytes, or E-164 phone numbers.  The  endpoint  discriminator
       sent to the peer by pppd can be set using the endpoint option.

       In  circumstances the peer may send no endpoint discriminator or a non-
       unique value.  The optional bundle option adds an extra string which is
       added  to  the peer's endpoint discriminator and authenticated identity
       when matching up links to be joined together in a bundle.   The  bundle
       option  can also be used to allow the establishment of multiple bundles
       between the local system and the peer.  Pppd uses  a  TDB  database  in
       /var/run/pppd.tdb to match up links.

       Assuming that multilink is enabled and the peer is willing to negotiate
       multilink, then when pppd is invoked to bring up the first link to  the
       peer,  it  will  detect that no other link is connected to the peer and
       create a new bundle, that is, another ppp network interface unit.  When
       another  pppd  is invoked to bring up another link to the peer, it will
       detect the existing bundle and join its link to it.  Currently, if  the
       first  pppd  terminates (for example, because of a hangup or a received
       signal) the bundle is destroyed.

 EXAMPLE S
       The following examples assume that the /etc/ppp/options  file  contains
       the  auth  option  (as  in the default /etc/ppp/options file in the ppp
       distribution).

       Probably the most common use of pppd is to dial out to  an  ISP.   This
       can be done with a command such as

              pppd call isp

       where the /etc/ppp/peers/isp file is set up by the system administrator
       to contain something like this:

              ttyS0 19200 crtscts
              connect '/usr/sbin/chat -v -f /etc/ppp/chat-isp'
              noauth

       In this example, we are using chat to  dial  the  ISP's  modem  and  go
       through  any  logon  sequence  required.   The  /etc/ppp/chat-isp  file
       contains the  script  used  by  chat;  it  could  for  example  contain
       something like this:

              ABORT "NO CARRIER"
              ABORT "NO DIALTONE"
              ABORT "ERROR"
              ABORT "NO ANSWER"
              ABORT "BUSY"
              ABORT "Username/Password Incorrect"
              "" "at"
              OK "at&d0&c1"
              OK "atdt2468135"
              "name:" "^Umyuserid"
              "word:" "\qmypassword"
              "ispts" "\q^Uppp"
              "~-^Uppp-~"

       See the chat(8) man page for details of chat scripts.

       Pppd  can  also be used to provide a dial-in ppp service for users.  If
       the users already have login accounts, the simplest way to set  up  the
       ppp  service  is to let the users log in to their accounts and run pppd
       (installed setuid-root) with a command such as

              pppd proxyarp

       To allow a user to use the PPP facilities, you need to allocate  an  IP
       address  for  that  user's machine and create an entry in /etc/ppp/pap-
       secrets or /etc/ppp/chap-secrets  (depending  on  which  authentication
       method  the PPP implementation on the user's machine supports), so that
       the user's machine can authenticate itself.  For example, if Joe has  a
       machine  called  "joespc"  which  is  to  be  allowed to dial in to the
       machine called "server" and use the IP address joespc.my.net, you would
       add  an  entry  like  this  to  /etc/ppp/pap-secrets  or /etc/ppp/chap-
       secrets:

              joespc    server    "joe's secret" joespc.my.net

       Alternatively, you can create a username called  (for  example)  "ppp",
       whose  login  shell  is  pppd  and  whose  home  directory is /etc/ppp.
       Options  to  be  used  when  pppd  is  run  this  way  can  be  put  in
       /etc/ppp/.ppprc.

        如果你的串列连线比直接以线路连接更复杂的话,你可能会需要做
       些调整以便避开一些控制字元。特别是,通常避开XON(^Q)以及
       XOFF(^S)是有用的,可以使用asyncmapa0000。如果该路径包
       含telnet的话,你可能应该也要避开^](asyncmap200a0000)。
       如果该路径包含rlogin的话,你将需要在执行rlogin的客户端
       上使用escapeff选项,因为许多rlogin的实作并非是透通的;
       它们将会从资料流中移除[0xff,0xff,0x73,0x73,跟随的任何
       8位元组]这些序列。

 DIAGNOSTICS
        讯息使用facilityLOG_DAEMON送到syslog隐形程式。(这个
       可以藉著以所要的facility定义LOG_PPP巨集来重新编译pppd
       加以改变。)为了能够看到错误以及侦错讯息,你将需要编寄愕
       /etc/syslog.conf档案来将讯息导向到所希望的设备或档案。

       debug选项使得所有送出以及接收的控制封包内容都被记录下来,
       这是指所有的LCP,PAP,CHAP,或是IPCP封包。如果PPP猩
       没有成功的话那麽这可能会有用。如果在编译时期开启侦错功能的
       话,pppd会使用facilityLOG_LOCAL2来取代LOG_DAEMON,而
       且debug选项会使得额外的侦错讯息被记录下来。

       侦错功能也可以藉著传送一个SIGUSR1到pppd程序来启动。侦
       错功能可以藉著传送一个SIGUSR2到pppd程序来关闭。

EXIT STATUS

       The exit status of pppd is  set  to  indicate  whether  any  error  was
       detected, or the reason for the link being terminated.  The values used
       are:

       0      Pppd has detached, or otherwise the connection was  successfully
              established and terminated at the peer's request.

       1      An  immediately  fatal  error  of some kind occurred, such as an
              essential system call failing, or running out of virtual memory.

       2      An  error  was detected in processing the options given, such as
              two mutually exclusive options being used.

       3      Pppd is not setuid-root and the invoking user is not root.

       4      The kernel does not support PPP, for  example,  the  PPP  kernel
              driver is not included or cannot be loaded.

       5      Pppd  terminated because it was sent a SIGINT, SIGTERM or SIGHUP
              signal.

       6      The serial port could not be locked.

       7      The serial port could not be opened.

       8      The connect script failed (returned a non-zero exit status).

       9      The command specified as the argument to the  pty  option  could
              not be run.

       10     The  PPP  negotiation failed, that is, it didn't reach the point
              where at least one network protocol (e.g. IP) was running.

       11     The peer system failed (or refused) to authenticate itself.

       12     The link was established successfully and terminated because  it
              was idle.

       13     The link was established successfully and terminated because the
              connect time limit was reached.

       14     Callback was negotiated  and  an  incoming  call  should  arrive
              shortly.

       15     The  link  was  terminated because the peer is not responding to
              echo requests.

       16     The link was terminated by the modem hanging up.

       17     The PPP negotiation failed because serial loopback was detected.

       18     The init script failed (returned a non-zero exit status).

       19     We failed to authenticate ourselves to the peer.

SCRIPTS

       Pppd  invokes  scripts at various stages in its processing which can be
       used to perform site-specific ancillary processing.  These scripts  are
       usually  shell  scripts,  but  could  be executable code files instead.
       Pppd does not wait for the scripts to finish.  The scripts are executed
       as  root  (with  the real and effective user-id set to 0), so that they
       can do things such as update routing tables or run privileged  daemons.
       Be  careful  that  the contents of these scripts do not compromise your
       system's security.  Pppd runs the scripts with standard  input,  output
       and  error  redirected  to  /dev/null,  and with an environment that is
       empty except for some environment variables that give information about
       the link.  The environment variables that pppd sets are:

       DEVICE The name of the serial tty device being used.

       IFNAME The name of the network interface being used.

       IPLOCAL
              The  IP address for the local end of the link.  This is only set
              when IPCP has come up.

       IPREMOTE
              The IP address for the remote end of the link.  This is only set
              when IPCP has come up.

       PEERNAME
              The  authenticated  name  of  the peer.  This is only set if the
              peer authenticates itself.

       SPEED  The baud rate of the tty device.

       ORIG_UID
              The real user-id of the user who invoked pppd.

       PPPLOGNAME
              The username of the real user-id  that  invoked  pppd.  This  is
              always set.

       For  the  ip-down  and  auth-down scripts, pppd also sets the following
       variables giving statistics for the connection:

       CONNECT_TIME
              The number of seconds from  when  the  PPP  negotiation  started
              until the connection was terminated.

       BYTES_SENT
              The  number  of  bytes  sent  (at  the level of the serial port)
              during the connection.

       BYTES_RCVD
              The number of bytes received (at the level of the  serial  port)
              during the connection.

       LINKNAME
              The logical name of the link, set with the linkname option.

       Pppd  invokes the following scripts, if they exist.  It is not an error
       if they don't exist.

       /etc/ppp/auth-up
              A program or script which is executed after  the  remote  system
              successfully  authenticates  itself.   It  is  executed with the
              parameters

              interface-name peer-name user-name tty-device speed

              Note that this script  is  not  executed  if  the  peer  doesn't
              authenticate itself, for example when the noauth option is used.

       /etc/ppp/auth-down
              A program or script which is executed when the link  goes  down,
              if  /etc/ppp/auth-up was previously executed.  It is executed in
              the same manner with the same parameters as /etc/ppp/auth-up.

       /etc/ppp/ip-up
              当线路可以传送以及接收IP封包时(也就是IPCP完成
              时)执行的一支程式或指令稿。它是以界面的名称、终端
              设备、速度、本地-IP-位址、远端-IP-位址为参数执行。

              interface-name  tty-device  speed  local-IP-address   remote-IP-
              address ipparam

       /etc/ppp/ip-down
              当线路不再允许传送以及接收IP封包时执行的一支程式
              或指令稿。这个指令稿可以用来回复/etc/ppp/ip-up指
              令稿的影响。它以与ip-up指令稿相同的参数启动。

       /etc/ppp/ipv6-up
              Like /etc/ppp/ip-up, except that it is executed when the link is
              available for sending and receiving IPv6 packets. It is executed
              with the parameters

              interface-name tty-device speed local-link-local-address remote-
              link-local-address ipparam

       /etc/ppp/ipv6-down
              Similar to  /etc/ppp/ip-down,  but  it  is  executed  when  IPv6
              packets can no longer be transmitted on the link. It is executed
              with the same parameters as the ipv6-up script.

       /etc/ppp/ipx-up
              A program or script which is executed when the link is available
              for  sending  and receiving IPX packets (that is, IPXCP has come
              up).  It is executed with the parameters

              interface-name tty-device speed  network-number  local-IPX-node-
              address    remote-IPX-node-address    local-IPX-routing-protocol
              remote-IPX-routing-protocol  local-IPX-router-name   remote-IPX-
              router-name ipparam pppd-pid

              The  local-IPX-routing-protocol  and remote-IPX-routing-protocol
              field may be one of the following:

              NONE      to indicate that there is no routing protocol
              RIP       to indicate that RIP/SAP should be used
              NLSP      to indicate that Novell NLSP should be used
              RIP NLSP  to indicate that both RIP/SAP and NLSP should be used

       /etc/ppp/ipx-down
              A program or script which is executed when the link is no longer
              available  for  sending  and receiving IPX packets.  This script
              can be used for  undoing  the  effects  of  the  /etc/ppp/ipx-up
              script.   It  is  invoked  in  the same manner and with the same
              parameters as the ipx-up script.

 FILES
       /var/run/pppn.pid (BSD or Linux), /etc/ppp/pppn.pid (others)
              在ppp界面单元n上的ppp程序之Process-ID。

       /var/run/ppp-name.pid (BSD or Linux), /etc/ppp/ppp-name.pid (others)
              Process-ID for pppd process  for  logical  link  name  (see  the
              linkname option).

       /etc/ppp/pap-secrets
               由PAP验证所使用的使用者名称、密码以及IP位址。  This file should
              be owned by root and not readable or writable by any other user.
              Pppd will log a warning if this is not the case.

       /etc/ppp/chap-secrets
               由CHAP验证所使用的名称、暗号以及IP位址。
               As  for /etc/ppp/pap-secrets, this file should be owned by root
              and not readable or writable by any other user.  Pppd will log a
              warning if this is not the case.

       /etc/ppp/options
               pppd的系统预设选项,在使用者预设选项或指令列选项之前读取。

       ~/.ppprc
               使用者预设选项,在指令列选项之前读取。

       /etc/ppp/options.ttyname
               所要使用之串列埠的系统预设选项,在指令列之後读取。read    after
              ~/.ppprc.  In forming the ttyname  part  of  this  filename,  an
              initial  /dev/  is stripped from the port name (if present), and
              any slashes in the remaining part are converted to dots.

       /etc/ppp/peers
              A  directory  containing  options  files   which   may   contain
              privileged  options,  even  if  pppd was invoked by a user other
              than root.  The system administrator can create options files in
              this  directory  to  permit  non-privileged  users  to  dial out
              without requiring the peer to authenticate, but only to  certain
              trusted peers.

 SEE ALSO
       RFC1144
              Jacobson,  V.   Compressing  TCP/IP headers for low-speed serial
              links.  February 1990.

       RFC1321
              Rivest, R.  The MD5 Message-Digest Algorithm.  April 1992.

       RFC1332
              McGregor, G.  PPP Internet  Protocol  Control  Protocol  (IPCP).
              May 1992.

       RFC1334
              Lloyd, B.; Simpson, W.A.  PPP authentication protocols.  October
              1992.

       RFC1661
              Simpson, W.A.  The Point-to-Point Protocol (PPP).  July 1994.

       RFC1662
              Simpson, W.A.  PPP in HDLC-like Framing.  July 1994.

       RFC2472
              Haskin, D.  IP Version 6 over PPP December 1998.

 NOTES
       下列信号传送到pppd程序时有特别的影响

       SIGINT, SIGTERM
              这些信号使得pppd终止该连线(关闭LCP),回存串列
              串列设备的设定,并结束离开。

       SIGHUP 指出实体层已颈欢舷摺ppd将会试图回存串列设备的设
              定(这可能会在Suns上产生错误讯息),然後结束离开。
               If the persist or demand option has been specified,  pppd  will
              try  to  reopen  the  serial device and start another connection
              (after the holdoff period).  Otherwise pppd will exit.  If  this
              signal  is received during the holdoff period, it causes pppd to
              end the holdoff period immediately.

       SIGUSR1
              This signal toggles the state of the debug option.

       SIGUSR2
              This signal causes pppd to renegotiate compression.  This can be
              useful  to re-enable compression after it has been disabled as a
              result of a fatal  decompression  error.   (Fatal  decompression
              errors generally indicate a bug in one or other implementation.)

 AUTHOR S
       Paul Mackerras (Paul.Mackerras@cs.anu.edu.au), based on earlier work by
       Drew Perkins, Brad Clements, Karl Fox, Greg Christy, and Brad Parker.

[inux Man <asdchen@pc2.hinet.net> <Best Linux> 1999

[1995/10/08

linuxan:
       http://cmpp.linuxforum.net

                                                                       PPPD(8)