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NAME

       pppd - 點對點協議守護進程

總覽 SYNOPSIS

       pppd [ tty_name ] [ speed ] [ options ]

描述

       點對點協議                    (PPP)                   提供一種在點對點串列線路上傳輸資料流
       (datagrams)的方法。PPP是由三個部份所組成的:一個在串列線
       路上封裝(encapsulating)資料流的方法,一個可延伸的連結控制
       協定(LinkControlProtocol:LCP),以及一些用來建立並配置不
       同網路層協定的網路控制協定(NetworkControlProtocols:NCP)

       封裝的機制(scheme)是由核心中的驅動程式碼來提供。pppd提供
       基本的LCP,驗證(authentication)的支援,以及一個用來建立
       並配置網際網路協定(InternatProtocol(IP))(叫做IP控制 協定,IPCP)的NCP。

 常用選項 FREQUENTLY USED OPTIONS
       <tty_name>
               在該名稱的設備上進行通訊。如果需要的話可以前置一個
              "/dev/"字串。如果沒有給設備名稱,pppd將會使用控制
              臺的終端機(controllingteriminal),並且產生(fork)出 來時將不會把自己放到背景去。

       <speed>
               將波特率設爲speed。在像是4.4BSD以及NetBSA的系
              統上,可以指定任何速率。其他系統(e.g.SunOs)只允 許有限的幾種速率。

       asyncmap <map>
               把非同步(async)字元設爲對照到。這個對照表
              描述哪些控制字元不能在串列線路上成功地接收。pppd將
              會要求彼端以兩個位元組的逸出序列(escapesequence)來
              傳送這些字元。其參數是32位元的十六進位數字而每個
              位元代表一個得避開(escape)的字元。位元0(00000001)
              代表字元0x00;位元31(80000000)代表字元0x1f或
              是^_。如果給了多個asyncmap選項,這些數值會以邏
              輯的或(OR)合在一起。如果沒有給asyncmap選項,將沒
              有非同步字元對照表會被加以協商來導引接收。這樣彼端 將會避開所有的控制字元。

       auth   要求彼端在允許傳送或接收網路封包之前先驗證它自己。 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
               使用以所指定的可執行指令或是shell指令來設定
              串列線路。這個指令稿一般會使用"chat"程式來撥數據 機並開始遠端ppp區段作業(session)。
              A value for this option from a privileged source cannot be  overridden  by  a  non-
              privileged user.

       crtscts
              使用硬體流量控制(i.e.RTS/CTS)來控制串列埠上的資料流。  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
               當IPCP協商完全成功時,增加一個預設遞送路徑到系統
              的遞送表,將彼端當作閘道器使用。這個項目在ppp連線 中斷後會移除。

       disconnect script
               在pppd已經終結該連線之後執行以所指定的可執行
              指令或是shell指令。這個指令稿可以用來,例如,如果
              硬體的數據機控制信號無法使用時,發出指令給數據機使   其掛斷電話。   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,...
               指定在傳輸上確實應該要避開的字元(不管對方是否有用
              它的非同步控制字元對照表要求避開它們)。這些要被避
              開的字元是以用逗號隔開的一串十六進位數字指定的。要
              注意到幾乎任何字元都可以用escape選項指定避開,不
              像asyncmap選項只允許指定控制字元。不能避開的字元
              是那些有十六進位值0x20-0x3f或是0x5e者。

       file name
               從檔案裏讀取選項(其格式敘述在後) 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應該在此串列設備上使用UUCP式的鎖定以確 定對該設備爲互斥(exclusive)存取。

       mru n  把MRU[MaximumReceiveUnit最大接收單元]的值設爲
              n來進行協商。pppd將會要求彼端傳送不比位元組
              更長的封包。最小的MRU值是128。預設的MRU值則是
              1500。對於慢速線路上的建議值是296(其中40個位元
              組給TCP/IP表頭+256個位元組的資料)。
               (Note that for IPv6 MRU must be at least 1280)

       mtu n
               將MTU[MaximumTransmitUnit最大傳輸單元]的值設
              爲n。除非彼端經由MRU協商要求一個更小的值,pppd
              將會要求核心網路程式碼透過PPP網路界面所傳送的資料 封包不超過n個位元組。
               (Note that for IPv6 MTU must be at least 1280)

       passive
               在LCP中開啓"passive"選項。加上這個選項,pppd將
              會試圖初使一個連線;如果沒有從彼端接收到迴應,那麼
              pppd將只會被動地等待從彼端所傳來的一個有效LCP封
              包(代替結束離開,就像它在沒有這個選項時所作的)。

選項 OPTIONS

       <local_IP_address>:<remote_IP_address>
               設定本地以及/或是遠端界面的IP位址。兩者之中的任
              何一個都可以省略。該IP位址可以利用主機名稱或者是
              十進位數值加小數點符號指定(e.g.150.234.56.78)。
              預設的本地位址是系統的(第一個)IP位址(除非有加上
              noipdefault選項)。遠端位址如果沒有在任何選項中指
              定的話將從彼端取得。因此,在簡單的案例中,這個選項
              不是必須的。如果有一個本地以及/或是遠端的IP位址
              以這個選項加以指定的話,pppd將不會接受在IPCP協商
              中從彼端所傳來不同的值,除非加上ipcp-accept-local            以及/或是ipcp-accept-
              remote選項,個別地。

       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
               如果有給這個選項,pppd將會每n 秒重新盤查彼端。

       chap-max-challenge n
               將CHAP盤查(challenge)傳輸的最大數目設爲n(預 設爲10)。

       chap-restart n
               將CHAP重新開始的間隔(重新傳輸的時間限制)設爲n 秒鐘(預設爲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  遞增偵錯層級(與-d相同)。如果加上這個選項,pppd
              將以可供閱讀的格式記錄所有傳送或接收的控制封包內容。
              這些封包透過syslog以facilitydaemon還有level
              debug加以記錄。該資訊可以適當設定/etc/syslog.conf
              來導向到一個檔案去。(參閱syslog.conf(5))。(如果
              pppd以開啓擴充偵錯(extradebugging)編譯的話,它將
              會使用facilitylocal2取代daemon來記錄訊息)。

       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
               新增領域名稱到本地主機名稱以支援驗證。例如,如
              果gethostname()迴應porsche這個名稱,但是完整合
              格的領域名稱是porsche.Quotron.COM的話,你可以使用
              domain選項來將領域名稱設爲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
              加上這個選項的話,pppd將會接受彼端對於本地IP位址
              的意見,即使本地的IP位址已經在某個選項中指定。

       ipcp-accept-remote
              加上這個選項的話,pppd將會接受彼端對於它的IP位址
              的意見,即使遠端的IP位址已經在某個選項中指定。

       ipcp-max-configure n
               將IPCP配置要求(configure-request)傳輸的最大數目設 爲n(預設爲10)。

       ipcp-max-failure n
              將開始傳送配置拒絕(configure-Rejects)之前的IPCP配               置未接收(configure-
              NAKs)的最大數目以取代n(預設 爲10)。

       ipcp-max-terminate n
               將IPCP終結要求(terminate-request)傳輸的最大數目設 爲 n(預設爲3)。

       ipcp-restart n
               將IPCP重新開始的間隔(重新傳輸的時間限制)設爲n 秒鐘(預設爲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
              開啓核心層級中的PPP驅動程式偵錯碼。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,  參數n是一個
              由下列值所組合的數字:1開啓一般偵錯訊息,2要求印
              出所接收到的封包內容,而4要求印出傳輸的封包內容。 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
               如果有給這個選項,那麼如果傳送n個LCP迴應要求沒
              有接收到有效的LCP迴應回覆的話pppd將會推測彼端是
              死掉的。如果發生這種情形,pppd將會終結該連線。這個     選項的使用要求一個非零的lcp-
              echo-interval參數值。            這個選項可以用在硬體數據機控制線路無法使用的情況下
              當實際連線被中斷之後(e.g.,數據機已經掛斷)終結 pppd的執行。

       lcp-echo-interval n
              如果有給這個選項,pppd每秒將會送出一個LCP回                            應要求(echo-
              request)封包(frame)給彼端。在Linux系
              統下,迴應要求在n秒內沒有從彼端接收到封包時會被送
              出。一般彼端應該以傳送一個迴應回覆(echo-reply)來反 應該回應要求。這個選項可以與lcp-
              echo-failure選項 一起使用來偵測不再連線的彼端。

       lcp-max-configure n
               將LCP配置要求(configure-request)傳輸的最大數目設 爲n(預設爲10)。

       lcp-max-failure n
               將開始傳送配置拒絕(configure-Rejects)之前的LCP配               置未接收(configure-
              NAKs)的最大數目設置爲n(預設 爲10)。

       lcp-max-terminate n
               將LCP終結要求(terminate-request)傳輸的最大數目設 爲n(預設爲3)。

       lcp-restart n
              將LCP重新開始的間隔(重新傳輸的時間限制)設爲 秒鐘(預設爲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  不要使用數據機控制線路。  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  使用系統密碼資料庫驗證使用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  使用數據機控制線路。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,這個選項會實作硬
              體流量控制,像crtsct選項作的。

       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
              將本地系統的名稱設爲用來進行驗證。 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
               把該界面網路掩碼設爲,這是一個以″十進位數值加
              小數點″("decimaldot")符號表示的32位元網路掩碼 (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
              關閉在沒有指定本地IP位址時所進行的預設動作,這是
              用來由從主機名稱決定(如果可能的話)決定本地IP位
              址。加上這個選項的話,彼端將必須在進行IPCP協商時
              (除非在指令列或在選項檔中明確地指定它)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
               將PAP驗證要求(authenticate-request)傳輸的最大數目 設爲n(預設爲10)。

       pap-restart n
               將PAP重新開始的間隔(重新傳輸的時間限制)設爲n 秒鐘(預設爲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位址以及該系統的乙太網路位址增加一個項
              目到系統的ARP[AddressResolutionProtocol位址解  譯協定]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
              將遠端系統的假設名稱設爲以進行驗證。

       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 加上這個選項,pppd將不會傳輸LCP封包來初使一個連
              線一直到從彼端接收到一個有效的LCP封包。(就像是給 舊版pppd使用的"passive"選項)。

       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
              強迫主機名稱使用本地系統的名稱來進行驗證。(這會蓋過name選項)。 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
              將使用者名稱設爲以便讓使用PAP的彼端驗證這臺機器時使用。

       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
              使用軟體流量控制(i.e.XON/XOFF)來控制串列埠上的資料流。

選項文件 OPTIONS FILES

       選項可以從檔案取出使用就如同使用命令列一般。pppd在查看指
       令列之前先從檔案/etc/ppp/options以及~/.ppprc讀取選項。  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.

       一個選項檔案以空白字元爲界被剖析成一串單字。空白字元可以用
       雙引號(")包括在一個單字裏。倒斜線引用其後的字元。而hash
       (#)符號開始一段註解持續到該行結束。  There  is  no  restriction  on using the file or call
       options within an options file.

安全 SECURITY

       pppd                                   提供系統管理人員充份的存取控制能力這表示以PPP存取一
       臺伺服機器可以提供給合法的使用者使用而不必擔心危及該伺服器
       或所在網路的安全性。這有一部份是以/etc/ppp/options檔案來
       提供,在這裏系統管理人員可以放置在執行pppd的時候用來要求
       驗證的選項,而部份是由PAP以及CHAP暗號檔案來提供,其中
       系統管理人員可以限制個別的使用者可以使用的一羣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預設的動作是如果有要求就同意進行驗證,並且不要求從彼
       端做驗證。然而如果沒有可以用來驗證的暗號則pppd將不會同意 以特殊的協定來驗證它自己。

        驗證的基礎是由暗號檔案選擇的暗號(/etc/ppp/pap-secrets是      給PAP使用的,/etc/ppp/chap-
       secrets則是給CHAP使用)。       這兩個暗號檔案都具有相同的格式,而且兩者都可以儲放暗號給數
       種伺服器(驗證彼端)及客戶(被驗證端)組合使用。注意pppd
       可以最爲伺服端以及客戶端,而且如果需要的話兩方可以使用不同 的協定。

        一個暗號檔案如同選項檔案一般被剖析成單字。一個暗號是由最少
       包含3個單字的一行所指定,依序是客戶,伺服器,暗號。在同
       一行中任何跟在其後的單字都被當作是給客戶的可接受IP位址列
       表。如果該行只有3個單字,這假設任何IP位址都可以;不允
       許所有的IP位址的話,使用"-"。如果暗號是以'@'開始,其
       後所接的單字將被假設爲可以從中讀取暗號的檔案名稱。而以一個
       "*"字元作爲客戶或伺服端的名稱會符合任何名稱。在選擇一個暗
       號時,pppd會選擇最符合的,i.e.最少萬用字元的那個。

       如此一個暗號檔案包含用來驗證其它主機,以及用來爲其它主機驗
       證自己兩者的暗號。選擇使用哪個暗號是根據該主機(本地名稱)
       以及其彼端(遠端名稱)而定。本地名稱的設定如下:

       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.

        當以PAP驗證彼端時,一個""暗號符合任何由彼端所提供密碼。
       如果密碼不符合暗號,密碼被以crypt()編碼並且再次檢查暗號;
       因此驗證彼端的暗號可以編碼方式儲放。

       如果指定有login選項,           使用者名稱以及密碼也會被以系統的密碼資料庫檢查。因此係統管
       理人員可以設定pap-secrets檔案以便只允許某些使用者以PPP
       連線,並且限制每個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.

        驗證必須在IPCP(或任何其它網路控制協定)開始之前被完全地
       滿足。如果驗證失敗,pppd將會終結連線(關閉LCP)。如果
       IPCP協商出一個無法接受的遠端主機IP位址,IPCP將會關閉。
       IP封包只有在IPCP打開的時候才能傳送或接收。

        即使本地主機一般會要求驗證,在某些案例中會希望允一些無法驗
       證它們自己的主機連線並使用所限制的IP位址其中之一。如果彼
       在被要求時拒絕驗證它自己,pppd將會把它當成等於是在使用者
       名稱以及密碼上使用空字串來以PAP驗證。所以,藉由增加一行     指定空字串爲客戶以及密碼到pap-
       secrets檔案去,允許拒絕驗 證自己的主機進行有限制的存取是可能的。

路由 ROUTING

        當IPCP協商成功地完成時,pppd將會通知核心該ppp界面本地
       以及遠端的IP位址。這足夠用來建立一個主機到該連線遠端的遞
       送路徑,該路徑將使兩端能交換IP封包。與其它的機器進行通訊
       往往需要更進一步地修改遞送表格(routingtables)以及/或是
       ARP(位址解譯協定)表格。在某些案例中這將透過routed或是
       gated隱形程式的動作自動地完成,但是在大部分的案例中需要更 進一步的介入。

        有時候會希望透過遠端主機來增加一個預設遞送路徑,像是在一臺
       只透過ppp界面連線到Internet的機器。此defaultroute選
       項使得pppd在IPCP完成時建立起這麼一個預設的遞送路徑,並 且在該線路被終結時將之刪除。

        在某些情況下會希望使用proxyARP,例如在一臺連結到區域網
       路的伺服機器上,爲了能夠允許其它的主機與遠端主機進行通訊。
       proxyarp選項引發pppd去尋找一個與遠端主機在相同子網路上
       的網路界面(一個支援廣播(boardcast)以及ARP的界面,不但要
       是可用的並且不是一個點對點或回授界面)。如果找到,pppd會
       以該遠端主機的IP位址以及所找到的網路界面之硬體位址建立一 個永久的,公開的ARP項目。

       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.

範例 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.

        如果你的串列連線比直接以線路連接更復雜的話,你可能會需要做
       些調整以便避開一些控制字元。特別是,通常避開XON(^Q)以及
       XOFF(^S)是有用的,可以使用asyncmapa0000。如果該路徑包
       含telnet的話,你可能應該也要避開^](asyncmap200a0000)。
       如果該路徑包含rlogin的話,你將需要在執行rlogin的客戶端
       上使用escapeff選項,因爲許多rlogin的實作並非是透通的;
       它們將會從資料流中移除[0xff,0xff,0x73,0x73,跟隨的任何 8位元組]這些序列。

診斷 DIAGNOSTICS

        訊息使用facilityLOG_DAEMON送到syslog隱形程式。(這個
       可以藉著以所要的facility定義LOG_PPP巨集來重新編譯pppd
       加以改變。)爲了能夠看到錯誤以及偵錯訊息,你將需要編輯你的
       /etc/syslog.conf檔案來將訊息導向到所希望的設備或檔案。

       debug選項使得所有送出以及接收的控制封包內容都被記錄下來,
       這是指所有的LCP,PAP,CHAP,或是IPCP封包。如果PPP協商
       沒有成功的話那麼這可能會有用。如果在編譯時期開啓偵錯功能的
       話,pppd會使用facilityLOG_LOCAL2來取代LOG_DAEMON,而
       且debug選項會使得額外的偵錯訊息被記錄下來。

       偵錯功能也可以藉著傳送一個SIGUSR1到pppd程序來啓動。偵
       錯功能可以藉著傳送一個SIGUSR2到pppd程序來關閉。

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
              當線路可以傳送以及接收IP封包時(也就是IPCP完成
              時)執行的一支程式或指令稿。它是以界面的名稱、終端
              設備、速度、本地-IP-位址、遠端-IP-位址爲參數執行。

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

       /etc/ppp/ip-down
              當線路不再允許傳送以及接收IP封包時執行的一支程式
              或指令稿。這個指令稿可以用來回復/etc/ppp/ip-up指              令稿的影響。它以與ip-
              up指令稿相同的參數啓動。

       /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.

文件 FILES

       /var/run/pppn.pid (BSD or Linux), /etc/ppp/pppn.pid (others)
              在ppp界面單元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驗證所使用的使用者名稱、密碼以及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驗證所使用的名稱、暗號以及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的系統預設選項,在使用者預設選項或指令列選項之前讀取。

       ~/.ppprc
               使用者預設選項,在指令列選項之前讀取。

       /etc/ppp/options.ttyname
               所要使用之串列埠的系統預設選項,在指令列之後讀取。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.

參見 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.

 注意 NOTES
       下列信號傳送到pppd程序時有特別的影響

       SIGINT, SIGTERM
              這些信號使得pppd終止該連線(關閉LCP),回存串列 串列設備的設定,並結束離開。

       SIGHUP 指出實體層已經被斷線。pppd將會試圖回存串列設備的設
              定(這可能會在Suns上產生錯誤訊息),然後結束離開。
               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.)

作者 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.

[中文版維護人]

       軟件教程之Linux Man <asdchen@pc2.hinet.net> <Best Linux> 1999

[中文版最新更新]

       1995/10/08

《中國linux論壇man手冊頁翻譯計劃》:

       http://cmpp.linuxforum.net

       本頁面中文版由中文 man 手冊頁計劃提供。
       中文 man 手冊頁計劃:https://github.com/man-pages-zh/manpages-zh

                                                                                          PPPD(8)