Provided by: tacacs+_4.0.4.26-3_amd64 bug

NAME

       tac_plus.conf - tacacs+ daemon configuration file

DESCRIPTION

       This page is a work in progress.

       tac_plus.conf contains configuration information for the tac_plus (tacacs+) daemon.

       Each  line  contains either one of the directives documented below, white-space (blanks or
       tabs), or a comment.

       Syntax enclosed in angle brackets (<>) below, refer to syntax documented elsewhere in this
       manual page.

TOP-LEVEL DIRECTIVES

       #      Comments  begin  with  a '#' character and extend to the end of the line.  Comments
              may appear anywhere in the configuration file.  To disable the special  meaning  of
              the '#' character, enclose the string containing it in double quotes ("#").

       accounting
              Only  one  configurable  account parameter exists, the destination.  All accounting
              records are either written to a file, syslog(3) at priority info, or both.

                  accounting syslog;
                  accounting file = <filename>

              The default filename is /var/log/tac_plus.acct.

              Since accounting requests occur (and are serviced) asynchronously, it is  necessary
              to  lock the accounting file so that two writers do not simultaneously write to it.
              The daemon uses fcntl(2) to lock the file.  Although fcntl(2) locking over  NFS  is
              supported  on  some  implementations,  it is notoriously unreliable.  Even if it is
              reliable, locking is likely to be extremely inefficient over NFS.  The file is best
              located on a local file system.

       acl    If  compiled  with acl support (--enable-acls), Access Control Lists can be defined
              to limit user's (or group's) login and/or enable access by daemon client IP address
              or  hostname.   An acl is referenced by its name, but must be defined before it can
              be referenced.

              The acl is a series of permit or deny statements applied to the source  IP  address
              that  the  client  used to connected to the daemon.  The first <regex> that matches
              ends the evaluation and the result is the permit or deny on left.  If no  entry  of
              the acl matches a given address, the result is an implicit deny.

                  acl = <name> {
                      <permission> = <regex>

                      # deny 66.1.255/24, allow all else in 66.1/16
                      deny = ^66\.1\.255\.
                      permit = ^66\.1\.
                      # implicit deny (ie: anything else)
                  }

              Briefly,  if a company had all their loopback interfaces numbered from 66.1/16 (and
              thus all the tacacs clients are within 66.1/16), this acl might  be  used  to  dis-
              allow  a  user to login to (or enable on) any router whose loopback interface is in
              66.1.255/24.

              Note: because acls match against the daemon client's source IP address, the  client
              should  be  configured  to  use  a stable source such as a loopback interface.  For
              example:
                  ip tacacs-server source-interface loopback 0

       default authentication
              By default, authentication fails for users that do not appear in the  configuration
              file.   This  overrides  that behavior, thus permitting all authentication requests
              for such users.

                  default authentication = file <filename>

              Such users will be authentication via the <user> "DEFAULT".

              Also see "user = DEFAULT", <default service>, and <default attribute>.

       group  Analogous to a <user> and accepting the same syntax, a group provides a template of
              which a <user> or another group can be a member.

                  group = <name> {
                      <user_decl>
                  }

              A group may be recursive; that is a group may be a member of one other group (which
              may be a member of yet another group, and so on).

       host   The host clause allows the configuration values noted  below  to  be  set  for  the
              client name by IP address.  If tac_plus is started with the -L option, the name can
              also be name as resolved from the address with the  gethostbyaddr(3)  system  call,
              which  may  be  the  FQDN  (Fully  Qualified  Domain  Name)  if DNS is used.  It is
              recommended that the IP address be used, since the resolver can be slow to  timeout
              when network faults exist.

                  host = <IP address> {
                   key = <string>
                   prompt = <string>
                   enable = <password_spec>
                  }

              key specifics the packet encryption <key> for this host.

              prompt specifies the username prompt that will be presented to a user.

       key    Specifies an encryption key used to encrypt packets between the daemon and clients.
              This key must match the key configured on the clients.

              key = <string>

              The double quotes are only necessary if your key contains  white-space,  key-words,
              or special characters.

              Note: encryption is highly recommended.

       logging
              Specifies  the  syslog(3) facility used.  By default, logs are posted to the daemon
              facility.

                  logging = <syslog_fac>

       user   Define a user whose username is <name>.

                  user = <name> {
                      [ <default service> ]
                      <user_attr>
                      <svc>
                  }

              Note: seventeen special  usernames  exist:  "DEFAULT",  "$enable$",  and  "$enabN$"
              (where  N is a privilege level number, normally in the range 0-15 on a Cisco).  The
              "$enable$" user is for backward compatibility with previous versions of tacacs that
              is queried for privilege level 15 in addition to "$enab15$".

              Also  see  the  "priv-lvl" AV pair in the "AV Pairs" section below and the <default
              authentication> directive.

       service
                  user = <string> {
                      [ default service = <permission> ]
                      <user_attr>*
                      <svc>*
                  }

              Also see the <default service> directive.

ADDITIONAL DIRECTIVE SYNTAX

       attr_value_pair
              Specify an AV (Attribute Value) pair.  The "optional" keyword specifies that the AV
              pair is optional.

                  [ optional ] <string> = <string>

              Optional  AV  pairs  are only sent to the client if it requests them.  That is, the
              client must have included the given AV pair as a mandatory or optional pair in  the
              request.

              Some clients react incorrectly and negatively to receiving AV pairs that it did not
              solicit.  Optional AV pairs should be ignored if they are  not  recognized  or  not
              supported in any given context.

              Also see the "Configuring Authorization" and "AV Pairs" sections below.

       cmd_auth
              Specify command authorization.

              For  command  authorization,  the  device should expand all abbreviated commands to
              their full names and compress adjacent white-space.  For example, when the  command
              "config t" is entered it will be expanded to "configure terminal".

                  cmd = <string> {
                      <cmd-match>
                  }

       cmd-match
              Specify a command argument match.

                  <permission> <regex>
                  <permission> <regex>
                   ...
                  <permission>

              The  <regex> matches arguments of the command <string>.  For example, to allow show
              diag but no other show commands:

                  cmd = show {
                      permit diag
                      deny
                  }

              The end of the <cmd-match> has an  implicit  <permission>  determined  by  <default
              service>.   So,  if the 'deny' had been omitted in the example above, the result of
              the authorization would be the value of <default service>.

              Note: 'cmd-arg' should never appear in a configuration file.  It is used internally
              by  the  daemon  to  construct  a  string which is then matched against the regular
              expressions which appear in a cmd clause in the configuration file.

              Note: when a command has multiple arguments, they may be entered in many  different
              permutations.   It  can  be  cumbersome  to  create  regular expressions which will
              reliably authorize commands under these conditions.   Administrators  may  wish  to
              consider other methods of performing authorization.

       default service
              Specifies the default <permission> for service authorization.

                  default service = <permission>

              If omitted, the default is 'deny'.

              Note:  if  used,  <default  service>  must  precede all other <svc> directives in a
              <user> clause.

       default attribute
              Specifies the default attribute <permission> for service authorization.

                  default attribute = <permission>

              Note: if used, <default attribute> must precede all other <svc_attr> directives  in
              a <svc> clause.

       des_string
              Represents  the one-way encryption of a password <string>.  For example, a password
              might encrypt to the string 0AmUKnIT2gheo.

              DES is the encryption historically used  in  Unix  passwd(5)  files.   The  crypt()
              function  of the system's libcrypt is used to perform the encryption.  The libcrypt
              of modern Unicies tend to support additional  encryption  algorithms  and  thus  so
              would  tac_plus.   See  the system's crypt manual page.  To utilize another format,
              use the des keyword followed by the  crypt  in  the  format  as  described  in  the
              manpage.   Typically  it will have a "$1" prefix for MD5, "$2" for blowfish, and so
              on.

              tac_pwd(8) is a utility  supplied  with  tac_plus  to  assist  in  performing  this
              encryption.

       expires
              Causes  the  <user>'s  password  to  become  invalid,  starting  on  the  specified
              expiration date.

                  expires "May 23 2005"

              A expiry warning message is sent to the user at login time,  starting  at  14  days
              before the expiration date.

              If  the  <user>'s  <login>  <password_spec>  is  "file", the "expires" field of the
              configuration file is not consulted.  Instead, the daemon looks at the the  "shell"
              field of the password file entry for a valid expiration date.

              If  Solaris  shadow password files are used for authentication, the "expires" field
              of the configuration file is not  consulted.  The  expiry  field  from  the  shadow
              password file (if it exists) is used as the expiration date.

              Case is not significant.

       filename
              A <string> specifying a file located in the filesystem.

              While  the daemon does change directories to / (root) when it starts, it is best to
              specify files by their FQPN (Fully Qualified Path Name).   That  is,  a  path  that
              begins   with  /.   For  example,  /var/log/file  rather  than  the  relative  path
              var/log/file.

       IP address
              A <string> representing an IPv4 address in dotted-quad notation.  For example:

                  192.168.1.1

       name   A <string> by which to refer to a configuration element, such  as  an  <acl>  or  a
              <group>.

              In  general,  a  <name>  must be defined before it can be referenced.  For example,
              before a <user> can be a specified as a member of a <group>, the <group> has to  be
              defined.

       password_spec
              There  are  five  authentication mechanisms available: no password, cleartext, DES,
              PAM, a file in passwd(5) format, and skey.

                  file <filename>
                  cleartext <string>
                  des <des_string>
                  PAM
                  skey
                  nopassword

              skey is an OTP (One Time Password) facility.  The daemon must be  built  with  skey
              (--enable-skey) support.

              PAM  (Pluggable  Authentication  Modules  framework) is an authentication mechanism
              (and much more) capable of various types of authentication methods that are  chosen
              by a configuration file.  The PAM service name is "tac_plus".  PAM can be used only
              for login authentication, it is not implemented for enable authorization, and  does
              not  support  OTP-like  challenge system (ie: no additional prompting).  The daemon
              must be built with PAM support, which is included by default if libpam is found.

              Note: some cases of <password_spec> do not accept all of these mechanisms.

       permission
              Specifies that some match (for example a <service> or <cmd-match>) is to be allowed
              or denied.

                  (permit | deny)

       proto  A  protocol is a subset of a service.  Typical NAS supported values are atalk, bap,
              bridging, ccp, cdp, deccp, ip, ipx, lat, lcp, multilink, nbf, osicp,  pad,  rlogin,
              telnet,  tn3270,  vines,  vpdn, xns, xremote, and unknown.  Note that 'protocol' is
              actually an AV pair.

       string A series of characters, not including white-space or tac_plus key-words or  special
              characters  (ie:  A-Za-z0-9_).   To  include  any  of those exceptions, enclose the
              string in double quotes ("this has whitespace").

       svc         XXX:

                  <svc_auth> | <cmd_auth>

       svc_auth
                   XXX:           service = ( arap | connection | exec | ppp protocol = <proto> |
                             shell   |   slip   |  system  |  tty-daemon  |  <client  defined>  )
                             {                [ <default attribute> ]
                                      <attr_value_pair>*
                                  }

              The service AV pair is required.

       syslog_fac
              syslog(3) normally has 16 well-known channels, called facilities.   syslogd(8)  can
              be  configured  to  direct  each  of  these  facilities  to  different  files.  The
              facilities are named: auth, cron, daemon,  local[0-7],  lpr,  mail,  news,  syslog,
              user, and uucp.

       user_attr
                   XXX:

                  user = bart {
                      arap = cleartext "arap password"
                      chap = cleartext "chap password"
                      enable = <password_spec>
                      pap  = cleartext "inbound pap password"
                      opap = cleartext "outbound pap password"
                      pap  = des <des_string>
                      pap  = file <filename>
                      pap  = PAM
                      login = <password_spec>
                      global = cleartext "outbound pap password"
                  }

              global  specifies  the  authentication  method  for all services.  login applies to
              normal logins (exec).  arap, chap, pap, and opap (outbound PAP)  service  passwords
              may be defined separately.

              NOTE:  a  global  user  password  cannot  be used for outbound PAP. This is because
              outbound PAP is implemented by sending the password from the daemon to the  client.
              This is a security issue if the <key> is ever compromised.

              enable  specifies  the  enable  password.   The <password_spec> may only be of type
              cleartext, des, nopassword or file.  If  the  daemon  was  compiled  with  per-user
              enable  support  (--enable-uenable), the host enable password will be evaluated iff
              the user does not have a personal enable password.

              login name member    - can only be 1 default service = permit expires "May 23 2005"
                  arap = cleartext "Fred's arap secret"
                  chap = cleartext "Fred's chap secret" acl = <string> enableacl = <string>

              In the case of recursion, the first match is returned.  host enable  is  cleartext,
              des,  nopassword or file only.  arap chap expires May 23 2005 login member password
                   user_attr :=           name     = <string> |
                                       login    = <password_spec> |
                                       member   = <string> |
                                       expires  = <string> |
                                       arap     = cleartext <string> |
                                       chap     = cleartext <string> |      #ifdef MSCHAP
                                       ms-chap  = cleartext <string> |      #endif
                                       pap      = cleartext <string> |
                                       pap      = des <string> |
                                       pap      = file <filename> |      #ifdef PAM
                                       pap      = PAM |      #endif
                                       opap     = cleartext <string> |
                                       global   = cleartext <string> |
                                       msg      = <string>
                                       before authorization = <string> |
                                       after authorization = <string>

CONFIGURING AUTHORIZATION

       Authorizing a single session can result in multiple requests being  sent  to  the  daemon.
       For  example,  to authorize a dialin ppp user for IP, the following authorization requests
       would be made from the client:

       1)     An initial authorization request to startup ppp from the exec, using the  AV  pairs
              service=ppp  protocol=ip,  will be made (Note: this initial request will be omitted
              if you are autoselecting ppp, since username will not be known yet).

              This request is really done to find the address for dumb PPP (or SLIP) clients  who
              cannot  do  address negotiation. Instead, they expect you to tell them what address
              to use before PPP starts up, via a text message.

       2)     Next, an authorization request is made from the PPP subsystem to see if  ppp's  LCP
              layer  is  authorized. LCP parameters can be set at this time (e.g. callback). This
              request contains the AV pairs service=ppp protocol=lcp.

       3)     Next an authorization request to startup ppp's IPCP layer  is  made  using  the  AV
              pairs service=ppp protocol=ipcp. Any parameters returned by the daemon are cached.

       4)     Next,  during PPP's address negotiation phase, each time the remote peer requests a
              specific address, if that address isn't in the cache obtained  in  step  3,  a  new
              authorization  request  is made to see if the peers requested address is allowable.
              This step can be repeated multiple times until  both  sides  agree  on  the  remote
              peer's address or until the NAS (or client) decide they're never going to agree and
              they shut down PPP instead.

       As you can see from the above, a program which plans to handle authorization must be  able
       to handle a variety of requests and respond appropriately.

       Authorization  must  be configured on both the client and the daemon to operate correctly.
       By default, the client will  allow  everything  until  configured  to  make  authorization
       requests to the daemon.

       With  the  daemon, the opposite is true; by default, the daemon will deny authorization of
       anything that isn't explicitly permitted.

       Authorization allows the daemon to deny commands  and  services  outright,  or  to  modify
       commands  and  services  on a per-user basis.  Authorization on the daemon is divided into
       two separate parts: commands and services.

       Authorizing:

       commands
              Exec commands are those commands which are typed  at  a  Cisco  exec  prompt.  When
              authorization is requested by the NAS, the entire command is sent to the daemon for
              authorization.

              Command authorization is configured by specifying  a  list  of  <regex>s  to  match
              command arguments and an action which is a <permission>.

              The following permits user Fred to run these commands:

                  telnet 131.108.13.<any number> and
                  telnet 128.<any number>.12.3 and
                  show <anything>

              All other commands are denied (by default).

                  user=fred {
                      cmd = telnet {
                          # permit specified telnets
                          permit 131\.108\.13\.[0-9]+
                          permit 128\.[0-9]+\.12\.3
                      }
                      cmd = show {
                          # permit show commands
                          permit .*
                      }
                  }

              The  command  and  arguments  which  the  user  types  are  matched  to the regular
              expressions specified in the configuration file  (in  order  of  appearance).   The
              first  successful  match performs the associated action (<permission>). If there is
              no match, the command is denied by default.

              Also  see  the  <default   authentication>,   <default   authorization>,   <default
              attribute>, and <default service> directives.

AUTHORIZATION SCRIPTS

       There  are  some  limitations  to the authorization that can be done using a configuration
       file.  One solution is to arrange for the daemon to call user-supplied programs to control
       authorization.  These  "callouts"  permit  almost  complete  control  over  authorization,
       allowing you to read all the fields in  the  authorization  packet  sent  by  the  client,
       including all its AV pairs, and to set authorization status and send a new set of AV pairs
       to the client in response.

       Pre and post authorization programs are invoked by handing the command line to the  Bourne
       shell.  On most Unix systems, if the shell doesn't find the specified program it returns a
       status of one, which denies authorization.  However,  at  least  one  Unix  system  (BSDI)
       returns a status code of 2 under these circumstances, which will permit authorization, and
       probably isn't what you intended.

       Note: if your program hangs, the authorization will time out and return an  error  on  the
       client,  and  you'll  tie  up a process slot on the daemon host, eventually running out of
       resources. There is no special code to detect this in the daemon.

       The daemon communicates with pre and post (before and after) authorization programs over a
       pair  of  pipes.  Programs using the standard i/o library will use full buffering in these
       circumstances.  This should not be a problem, since AV pairs will be  read  until  end  of
       file (EOF) is seen on input, and output will be flushed when they exit.

       Fields  from  the authorization packet can be supplied to the programs as arguments on the
       command line by using the appropriate dollar-sign variables  in  the  configuration  file.
       These fields are:

           user    -- user name
           name    -- client/NAS name
           ip      -- client/NAS IP
           port    -- client/NAS port
           address -- user address (remote user location)
           priv    -- privilege level number (0-15)
           method  -- a digit (1-4)
           type    -- digit (1-4)
           service -- digit (1-7)
           status  -- (pass, fail, error, unknown)

       Unrecognized variables will appear as the string "unknown".

       AV  pairs  from  the authorization packet are fed to the program's standard input, one per
       line. The program is expected to process the AV pairs  and  write  them  to  its  standard
       output, one per line. What happens then is determined by the exit status of the program.

       Note:  when  AV  pairs containing spaces are listed in the configuration file, you need to
       enclose them in double quotes so that they  are  parsed  correctly.  AV  pairs  which  are
       returned  via  standard  output  do  not  need delimiters and so should not be enclosed in
       double quotes.

       Note: unless special arrangements are made, the daemon will run  as  root  and  hence  the
       programs  it  invokes  will also run as root, which is a security weakness. It is strongly
       recommended that FQPNs are used when specifying programs to execute, and that  the  daemon
       is  compiled  with  unprivileged  user and group IDs (--with-userid and --with-groupid) so
       that the daemon is not running as root when calling these programs,

       Calling scripts

       before authorization
              Specify a per-user program to be called before any other authorization  attempt  is
              made by using a "before" clause.

                  user = auth1 {
                      before authorization "/path/pre_authorize $user $port $address"
                  }

              The  AV pairs sent from the NAS will be supplied to the program standard input, one
              pair per line.

              If the program returns a status of 0, authorization is  unconditionally  permitted.
              No  further  processing is done on this request and no AV pairs are returned to the
              client.

              If the program returns a status of 1, authorization is unconditionally  denied.  No
              further  processing  is  done  on  this request and no AV pairs are returned to the
              client.

              If the program returns a status of 2, authorization is permitted.  The  program  is
              expected  to  modify  the  AV  pairs  that it receives on its standard input (or to
              create entirely new ones) and to write them, one per line, to its standard  output.
              The   new   AV   pairs   will   be   sent   to   the   client   with  a  status  of
              AUTHOR_STATUS_PASS_REPL.  No further processing takes place on this request.

              If the program returns a status of 3, authorization is denied, but  all  attributes
              returned  by  the program via stdout are returned to the client. Also, whatever the
              program returns on stderr is placed into the server-msg field and returned  to  the
              client.

              Any other status value returned from the program will cause an error to be returned
              to the client.

              Note: a status of 2 is not acceptable when doing command authorization.

       after authorization
              Specify a per-user program to be called after  authorization  processing  has  been
              performed  by  the  default,  but before the authorization status and AV pairs have
              been transmitted to the client, by using a "after" clause.

                  group = auth1 {
                      after authorization "/path/post_authorize $user $port $status"
                  }

              The AV pairs resulting from the authorization algorithm that the daemon proposes to
              return  to  the NAS, are supplied to the program on standard input, one AV pair per
              line, so they can be modified if required.

              The program is expected to process the AV pairs and  write  them  to  its  standard
              output,  one  per  line.  What happens then is determined by the exit status of the
              program:

              If the program returns a status of 0, authorization continues as if the program had
              never  been  called.   Use  this  if  (for  example)  to  just  send  mail  when an
              authorization occurs, without otherwise affecting normal authorization.

              If the program returns a status of 1, authorization is unconditionally  denied.  No
              AV  pairs  are  returned  to the NAS. No further authorization processing occurs on
              this request.

              If the program returns a status of 2, authorization is permitted and any  AV  pairs
              returned  from  the  program on its standard output are sent to the NAS in place of
              any AV pairs that the daemon may have constructed.

              Any other value will cause an error to be returned to the NAS by the daemon.

       Current attributes are:

           "unknown"
           "service"
           "start_time"
           "port"
           "elapsed_time"
           "status"
           "priv_level"
           "cmd"
           "protocol"
           "cmd-arg"
           "bytes_in"
           "bytes_out"
           "paks_in"
           "paks_out"
           "address"
           "task_id"
           "callback-dialstring"
           "nocallback-verify"
           "callback-line"
           "callback-rotary"

       Also see the "AV Pairs" section below.

AV PAIRS

       AV (Attribute Value) pairs are text strings exchanged between the client and server of the
       form  "attribute=value".   The  value  may  not  appear  in authorization request packets,
       indicating that it is null or unspecified.  The equal sign ('=')  means  that  this  is  a
       mandatory  attribute.  An asterisk ('*') may appear in place of the equal sign, indicating
       that it is an optional attribute which either the client or server may not  understand  or
       may ignore.

       Optional  attributes  are  preceded  by the "optional" key-word in the configuration.  For
       example:

           priv_lvl = 15
           optional allow-shell = true

           service=ppp
           protocol=ip
           addr*131.108.12.44

       The following AV pairs specify which service  is  being  authorized.  They  are  typically
       accompanied by protocol AV pairs and other, additional pairs from the lists below.

       service=arap

       service=shell       for exec startup, and also for command authorizations.  Requires:

                               aaa authorization exec tacacs+

       service=ppp

       service=slip

       service=system      not used.

       service=raccess     Used for managing reverse telnet connections e.g.

                               user = jim {
                                   login = cleartext lab
                                   service = raccess {
                                       port#1 = clientname1/tty2
                                       port#2 = clientname2/tty5
                                   }
                               }

                           Requires IOS configuration

                               aaa authorization reverse-access tacacs+

       protocol=lcp        The  lower  layer  of  PPP, always brought up before IP, IPX, etc.  is
                           brought up.

       protocol=ip         Used with service=ppp and  service=slip  to  indicate  which  protocol
                           layer is being authorized.

       protocol=ipx        Used  with  service=ppp  to  indicate  which  protocol  layer is being
                           authorized.

       protocol=atalk      with service=ppp or service=arap

       protocol=vines      For vines over ppp.

       protocol=ccp        Authorization of CCP.  Compression Control  Protocol).  No  other  AV-
                           pairs associated with this.

       protocol=cdp        Authorization  of  CDP  (Cisco  Discovery Protocol). No other av-pairs
                           associated with this.

       protocol=multilink  Authorization of multilink PPP.

       protocol=unknown    For undefined/unsupported conditions. Should not  occur  under  normal
                           circumstances.

       Incomplete list of Cisco AV pairs.  Other vendors may provide additional AV pairs specific
       to their products.

       acl    For EXEC authorization this  contains  an  access-class  number  (acl=2)  which  is
              applied  to  the  line (tty) as the output access class.  The specified access-list
              must be predefined.

              ARAP, EXEC.

       addr   The IP address the remote host should be assigned when a slip or PPP/IP  connection
              is made.  For example: addr=1.2.3.4

              SLIP, PPP/IP.

       autocmd
              During  exec startup, this specifies an autocommand, like the autocommand option to
              the username configuration command.  For example: autocmd="telnet foo.com"

              EXEC.

       callback-line
              The number of a TTY line to use for the callback.  Used  with  service=arap,  slip,
              ppp, or shell.  Does not work for ISDN.

       callback-rotary
              The  number  of  a rotary group (0 through 100) to use for the callback.  Used with
              service=arap, slip, ppp, and shell.  Does not work for ISDN.

       cmd    If the value of cmd is NULL (cmd=), then  this  is  an  authorization  request  for
              starting an exec.

              If  cmd is non-null, this is a command authorization request.  It contains the name
              of the command being authorized.  For example: cmd=telnet

              EXEC.

       cmd-arg
              During command authorization, the name of the command is given by  an  accompanying
              "cmd="  AV pair, and each command argument is represented by a cmd-arg AV pair e.g.
              cmd-arg=archie.sura.net

              NOTE: 'cmd-arg' should never appear in a configuration file.  It is used internally
              by  the  daemon  to  construct  a  string which is then matched against the regular
              expressions which appear in a cmd clause in the configuration file.

              EXEC.

       dns-servers
              Identifies a primary or backup DNS server that can be requested  by  Microsoft  PPP
              clients during IPCP negotiation.  Used with service=ppp and protocol=ip.

       gw-password
              Specifies the password for the home gateway during L2F tunnel authentication.  Used
              with service=ppp and protocol=vpdn.

       idletime
              Sets a value, in minutes, after which an IDLE session will be terminated.  Does NOT
              work for PPP.

              EXEC, 11.1 onward.

       inacl  This  AV  pair  contains  an  IP  or  IPX  input access list number for slip or PPP
              (inacl=2). The access list itself must be pre-configured on the Cisco box. Per-user
              access  lists  do not work with ISDN interfaces unless you also configure a virtual
              interface. After 11.2(5.1)F, you can also use the name of a predefined named access
              list, instead of a number, for the value of this attribute.

              Note: For IPX, inacl is only valid after 11.2(4)F.

              PPP/IP/IPX.

       inacl#<n>
              This  AV  pair  contains the definition of an input access list to be installed and
              applied to an interface for the duration of the current connection, e.g.

                  inacl#1="permit ip any any precedence immediate"
                  inacl#2="deny igrp 0.0.1.2 255.255.0.0 any"

              Attributes are sorted numerically before they are applied.   For  IP,  standard  OR
              extended access list syntax may be used, but it is an error to mix the two within a
              given access-list.

              For IPX, only extended access list syntax may be used.

              PPP/IP/PPP/IPX, 11.2(4)F.

       interface-config
              Specifies  user-specific  AAA  interface  configuration  information  with  Virtual
              Profiles.   The  information  that  follows the equal sign (=) can be any Cisco IOS
              interface configuration command.

       ip-address
              List of possible IP addresses, separated by spaces, that can be used for  the  end-
              point of a tunnel.  Used with service=ppp and protocol=vpdn.

       link-compression
              Defines  whether  to  turn  on or turn off Stac compression over a PPP link.  Valid
              values are:

                   0    None
                   1    Stac
                   2    Stac Draft-9
                   3    MS-Stac

       load-threshold
              This AV pair sets the load threshold at which an additional multilink link is added
              to the bundle (if load goes above) or deleted (if load goes below).

                  service=ppp protocol=multilink {
                      load-threshold=<n>
                  }

              The range of <n> is [1-255].

              PPP/multilink - Multilink parameter, 11.3.

       max-links
              This AV pair restricts the number of multilink bundle links that a user can have.

                  service=ppp protocol=multilink {
                      max-links=<n>
                  }

              The range of <n> is [1-255].

              PPP/multilink, 11.3.

       nas-password
              Specifies  the  password  for  the NAS during L2F tunnel authentication.  Used with
              service=ppp and protocol=vpdn.

       nocallback-verify
              Indicates that no callback verification is required. The only valid value for  this
              parameter  is  the  digit  one,   i.e.   nocallback-verify=1.   Not valid for ISDN.
              ARAP/EXEC, 11.1 onward.

       noescape
              During exec startup, this specifies "noescape", like the  noescape  option  to  the
              username  configuration  command.   Can  have  as  its  value  the string "true" or
              "false".  For example: noescape=true

              EXEC.

       nohangup
              During exec startup, this specifies "nohangup", like the  nohangup  option  to  the
              username  configuration  command.   Can  have  as  its  value  the string "true" or
              "false".  For example: nohangup=true

              EXEC.

       old-prompts
              Allows the prompts in TACACS+ to appear  identical  to  those  of  earlier  systems
              (TACACS  and  Extended  TACACS).   This  allows the upgrade from TACACS or Extended
              TACACS to TACACS+ to be transparent to users.

       outacl This AV pair contains an IP or IPX output access list number for  SLIP.  PPP/IP  or
              PPP/IPX  connections  (outacl=4).  The  access  list itself must be pre-configured.
              Per-user access lists do not work with ISDN interfaces unless you also configure  a
              virtual interface.  PPP/IPX is supported in 11.1 onward only. After 11.2(5.1)F, you
              can also use the name of a predefined named access list, as well as a  number,  for
              the value of this attribute.

              PPP/IP, PPP/IPX.

       outacl#<n>
              This  AV pair contains an output access list definition to be installed and applied
              to an interface for the duration of the current connection.

                  outacl#1="permit ip any any precedence immediate"
                  outacl#2="deny igrp 0.0.9.10 255.255.0.0 any"

              Attributes are sorted numerically before they are applied.   For  IP,  standard  OR
              extended access list syntax may be used, but it is an error to mix the two within a
              given access-list.

              For IPX, only extended access list syntax may be used.

              PPP/IP/PPP/IPX, 11.2(4)F.

       pool-def#
              Defines IP address pools on the NAS.  Used with service=ppp and protocol=ip.

       pool-timeout
              In conjunction with pool-def, defines IP address pools on  the  NAS.   During  IPCP
              address  negotiation, if an IP pool name is specified for a user (see the addr-pool
              attribute), a check is made that the named pool is defined on the NAS.  If  it  is,
              the pool is consulted for an IP address.

       ppp-vj-slot-compression
              Instructs  the  Cisco router not to use slot compression when sending VJ-compressed
              packets over a PPP link.

       priv-lvl
              Specifies the current privilege level for command  authorizations,  a  number  from
              zero to 15.  For example: priv_lvl=5.

              Note: in 10.3 this attribute was priv_lvl, i.e.  it contained an underscore instead
              of a hyphen.

              EXEC.

       route  This AV pair specifies a temporary static route to be applied, which expunged  once
              the connection terminates.  The daemon side declaration is:

                  service=ppp protocol=ip {
                      route="<dst_addr> <mask> [ <gateway> ]"
                  }

              <dst_address>,  <mask>,  and  <gateway>  are  <IP  address>'s.   If  the gateway is
              omitted, the peer's address is assumed.

              PPP/IP/SLIP, 11.1 onward.

       route#<n>
              Same as the "route" attribute, except that these are valid for IPX as well  as  IP,
              and they are numbered, allowing multiple routes to be applied.  For example:

                  route#1="3.0.0.0 255.0.0.0 1.2.3.4"
                  route#2="4.0.0.0 255.0.0.0"

              or, for IPX,

                  route#1="4C000000 ff000000 30.12.3.4"
                  route#2="5C000000 ff000000 30.12.3.5"

              PPP/IP/IPX, 11.2(4)F.

       routing
              Equivalent to the /routing flag in slip and ppp commands. Can have as its value the
              string "true" or "false".

              SLIP/PPP/IP.

       rte-ftr-in#
              Specifies an input access list definition to be installed and  applied  to  routing
              updates  on the current interface for the duration of the current connection.  Used
              with service=ppp protocol=ip or protocol=ipx.

       rte-ftr-out#
              Output version of rte-ftr-in#.

       sap#<n>
              This AV pair specifies static SAPs (Service Advertising Protocol) to  be  installed
              for the duration of a connection.  For example:

                  sap#1="4 CE1-LAB 1234.0000.0000.0001 451 4"
                  sap#2="5 CE3-LAB 2345.0000.0000.0001 452 5"

              The  syntax  of  static saps is the same as that used by the IOS "ipx sap" command.
              Used with service=ppp protocol=ipx.

              PPP/IPX, 11.2(4)F.

       sap-fltr-in#<n>
              This AV pair specifies an input SAP filter access list definition to  be  installed
              and applied to the current interface, for the duration of the current connection.

              Only  Cisco  extended  access list syntax is legal (ipx input-sap-filter <number>).
              For example:

                  sap-fltr-in#1="deny 6C01.0000.0000.0001"
                  sap-fltr-in#2="permit -1"

              Attributes are sorted numerically before  being  applied.   Used  with  service=ppp
              protocol=ipx.

              PPP/IPX, 11.2(4)F.

       sap-fltr-out#<n>
              This  AV pair specifies an output sap filter access list definition to be installed
              and applied on the current interface, for the duration of the current connection.

              Only Cisco extended access list syntax is legal (ipx  output-sap-filter  <number>),
              e.g

                  sap-fltr-out#1="deny 6C01.0000.0000.0001"
                  sap-fltr-out#2="permit -1"

              Attributes  are  sorted  numerically  before  being applied.  Used with service=ppp
              protocol=ipx.

              PPP/IPX, 11.2(4)F.

       source-ip
              This specifies a single ip address that will be used as  the  source  of  all  VPDN
              packets  generated as part of the VPDN tunnel (see the equivalent source-ip keyword
              in the IOS vpdn outgoing command).

              PPP/VPDN, now deprecated, only existed in releases 11.2(1.4) thru 11.2(4.0.2).

       timeout
              Sets the time until  an  ARAP  or  exec  session  disconnects  unconditionally  (in
              minutes).  For example: timeout=60

              ARAP/EXEC, 11.0 onward.

       tunnel-id
              This  AV  pair  specifies the username that will be used to authenticate the tunnel
              over which the individual user MID will be projected.  This  is  analogous  to  the
              "NAS name" in the "vpdn outgoing" command.

              PPP/VPDN, 11.2 onward.

       zonelist
              An  Appletalk zonelist for arap (ARAP) equivalent to the line configuration command
              "arap zonelist".  For example: zonelist=5.

       AV pairs reserved for future use (this list may be out-dated):

           ppp-vj-slot-compression
           link-compression
           asyncmap
           x25-addresses (PPP/VPDN)
           frame-relay (PPP/VPDN)

       Note: this AV pair list is NOT complete and not all AV pairs are supported by all vendors.
       See  the  vendor's  documentation.  When a client (or server) receives a mandatory AV pair
       that it does not understand, the authorization FAILS!

       Also see the tac_plus user guide.   Some  of  the  callback,  appletalk,  IPX,  VPDN,  PPP
       routing, and address pool related AV pairs found in the user guide have been omitted.

ACCOUNTING AV PAIRS

       bytes_in            The number of input bytes transferred during this connection.

       bytes_out           The number of output bytes transferred during this connection.

       cmd                 The command the user executed.

       data-rate           This AV pair has been renamed. See nas-rx-speed.

       disc-cause          Specifies the reason a connection was taken off-line.  The Disconnect-
                           Cause attribute is sent in accounting stop  records.   This  attribute
                           also  causes  stop  records  to  be generated without first generating
                           start records if disconnected before authentication.

                                1    User request
                                2    Lost carrier
                                3    Lost service
                                4    Idle timeout
                                5    Session timeout
                                6    Admin reset
                                7    Admin reboot
                                8    Port error
                                9    NAS error
                                10   NAS request
                                11   NAS reboot
                                12   Port unneeded
                                13   Port pre-empted
                                14   Port suspended
                                15   Service unavailable
                                16   Callback
                                17   User error
                                18   Host request

       disc-cause-ext      Extends the disc-cause attribute to  support  vendor-specific  reasons
                           that a connection was taken off-line.

                                1000 Session timed out. This value applies to all session types.
                                1002 Reason unknown.
                                1004 Failure to authenticate calling-party number.
                                1010 No carrier detected. This value applies to modem connections.
                                1011 Loss of carrier. This value applies to modem connections.
                                1012 Failure to detect modem result codes. This value applies to modem connections.
                                1020 User terminates a session. This value applies to EXEC sessions.
                                1021 Timeout waiting for user input. This value applies to all session types.
                                1022 Disconnect due to exiting Telnet session. This value applies to EXEC sessions.
                                1023 Could not switch to SLIP/PPP; the remote end has no IP address. This value applies to EXEC sessions.
                                1024 Disconnect due to exiting raw TCP. This value applies to EXEC sessions.
                                1025 Bad passwords. This value applies to EXEC sessions.
                                1026 Raw TCP disabled. This value applies to EXEC sessions.
                                1027 Control-C detected. This value applies to EXEC sessions.
                                1028 EXEC process destroyed. This value applies to EXEC sessions.
                                1040 PPP LCP negotiation timed out. This value applies to PPP sessions.
                                1041 PPP LCP negotiation failed.
                                1042 PPP PAP authentication failed.
                                1043 PPP CHAP authentication failed.
                                1044 PPP remote authentication failed.
                                1045 PPP received a Terminate Request from remote end.
                                1046 Upper layer requested that the session be closed.  This value applies to PPP sessions.
                                1101 Session failed for security reasons. This value applies to all session types.
                                1102 Session terminated due to callback. This value applies to all session types.
                                1120 Call refused because the detected protocol is disabled. This value applies to all session types.

       elapsed_time        The  elapsed  time  in  seconds for the action. Useful when the device
                           does not keep real time.

       event               Information included in the accounting packet that describes  a  state
                           change  in  the  router.  Events described are accounting starting and
                           accounting stopping.

       mlp-links-max       Gives the count of links known to  have  been  in  a  given  multilink
                           session at the time the accounting record is generated.

       mlp-sess-id         Reports  the  identification  number  of the multilink bundle when the
                           session closes.  This attribute applies to sessions that are part of a
                           multilink  bundle.   This attribute is sent in authentication-response
                           packets.

       nas-rx-speed        Specifies the average number of bits per second over the course of the
                           connection's  lifetime.   This  attribute  is  sent in accounting stop
                           records.

       nas-tx-speed        Reports the transmit speed negotiated by the two modems.

       paks_in             The number of input packets transferred during this connection.

       paks_out            The number of output packets transferred during this connection.

       port                The port into which the user was logged.

       pre-bytes-in        Records  the  number  of  input  bytes  before  authentication.   This
                           attribute is sent in accounting stop records.

       pre-bytes-out       Records  the  number  of  output  bytes  before  authentication.  This
                           attribute is sent in accounting stop records.

       pre-paks-in         Records the  number  of  input  packets  before  authentication.  This
                           attribute is sent in accounting stop records.

       pre-paks-out        Records  the  number  of  output  packets before authentication.  This
                           attribute is sent in accounting stop records as Pre-Output-Packets.

       pre-session-time    Specifies the length of time, in  seconds,  from  when  a  call  first
                           connects to when it completes authentication.

       priv_level          The privilege level associated with the action.

       protocol            The protocol associated with the action.

       reason              Information included in the accounting packet that describes the event
                           that caused a system change.   Events  described  are  system  reload,
                           system shutdown, or accounting reconfiguration (turned on or off).

       service             The service the user used.

       start_time          The time, in seconds since 12:00 a.m. January 1, 1970, that the action
                           started.  The clock must be configured to receive this information.

       stop_time           The time, in seconds since 12:00 a.m. January 1, 1970, that the action
                           stopped.  The clock must be configured to receive this information.

       task_id             Start  and stop records for the same event must have matching (unique)
                           task_id numbers.

       timezone            The time zone abbreviation for all timestamps included in this packet.

       xmit-rate           This AV pair has been renamed nas-tx-speed.

EXAMPLE CLIENT CONFIGURATION

       Example Cisco configuration for tacacs+:

           aaa new-model
           aaa authentication login default tacacs+ local
           aaa authentication enable default tacacs+ enable
           aaa authorization exec default tacacs+
           aaa accounting exec default start-stop tacacs+
           !
           username root privilege 15 password 0 <root's password>
           !
           tacacs-server key <your key here>
           tacacs-server host <ip_address>
           ip tacacs source-interface loopback0
           !
           enable secret 0 <enable password>

       Note that the aaa command syntax varies slightly between some versions of  Cisco  IOS  and
       CatOS (Catalyst OS) also varies.

       Example Juniper configuration for tacacs+:

           system {
               authentication-order [ password tacplus ];
               tacplus-server {
                   <ip_address> secret <your key here>;
                   <ip_address> {
                       secret <your key here>;
                       timeout 90;
                   }
               }
           }

       Both  of  these  examples  are brief.  See the vendor's documentation for a description of
       what these configuration commands specify and for additional commands and arguments.

       WARNING:  If not properly configured, it may not be possible to login to the device!

EXAMPLE TAC_PLUS CONFIGURATION

       key = "your key here"
       accounting file = /var/log/tac.acct
       # authentication users not appearing elsewhere via
       # the file /etc/passwd
       default authentication = file /etc/passwd

       acl = dial_only {
           # All access routers are in 192.168/16, but except for
           # 192.168.0.1 all backbone router are in 198.168.0/24.
           # deny access to the backbone routers.
           permit = ^192\.168\.0\.1$
           deny   = ^192\.168\.0\.
           permit = ^192\.168\.
       }

       group = no_backbone {
           # permit an exec to start and permit all commands and
           # services by default
           default service = permit

           service = exec {
               # When an exec is started, its connection access list
               # will be 4. "acl" is quoted because it is a keyword.
               # It also has an autocmd
               "acl" = 4
               autocmd = "telnet duffhost"
           }

           # group will only be allowed to login on NASes
           acl = dial_only
       }
       group = admin {
           # group members who don't have their own login password will be
           # looked up in /etc/passwd
           login = file /etc/passwd

           # group members who have no expiry date set will use this one
           expires = "Jan 1 1997"

           # deny access to backbone routers
           acl = dial_only
       }

       user = DEFAULT {
           service = ppp protocol = ip {
               addr-pool=foobar
           }
       }
       user = homer {
           default service = permit

           member = no_backbone
       }
       user = fred {
           login = des mEX027bHtzTlQ
           name = "Fred Flintstone"
           member = admin
           expires = "May 23 2005"
           arap = cleartext "Fred's arap secret"
           chap = cleartext "Fred's chap secret"

           service = exec {
               # When Fred starts an exec, his connection access
               # list is 5
               "acl" = 5

               # We require this autocmd to be done at startup
               autocmd = "telnet foo"
           }

           # All commands except show system are denied for Fred
           cmd = show {
               # Fred can run the following show command

               permit system
               deny .*
           }

           service = ppp protocol = ip {
               # Fred can run ip over ppp only if he uses one
               # of the following mandatory addresses. If he
               # supplies no address, the first one here will
               # be mandated

               addr=131.108.12.11
               addr=131.108.12.12
               addr=131.108.12.13
               addr=131.108.12.14

               # Fred's mandatory input access list number is 101
               inacl=101

               # We will suggest an output access list of 102, but the NAS may
               # choose to ignore or override it

               optional outacl=102
           }

           service = slip {
               # Fred can run slip. When he does, he will have to use
               # these mandatory access lists

               inacl=101
               outacl=102
           }
       }

       user = wilma {
           # Wilma has no password of her own, but she's a group member so
           # she'll use the group password if there is one. Same for her
           # password expiry date

           member = admin
       }

FILES

       /etc/tac_plus.conf            Configuration file.

       /var/log/tac_plus.acct        The default accounting file.

       /var/log/tac_plus.log         The default log file.

SEE ALSO

       gethostbyaddr(3), passwd(5), regexp(3), tac_plus(8), tac_pwd(8)

       Also see the tac_plus User Guide (user_guide) that came with the distribution.   The  user
       guide  does  not  cover  all the modifications to the original Cisco version nor does this
       manual page cover everything that is  in  the  user  guide  (callback  configuration,  for
       example).

AUTHOR

       The  tac_plus  (tacacs+) developer's kit is a product of Cisco Systems.  Made available at
       no cost and with no warranty of any kind.  See the file COPYING and source files that came
       with the distribution for specifics.

HISTORY

       This manual page was adapted from code inspection and Cisco's tac_plus user guide.

BUGS

       This manual page is incomplete.

                                           6 June 2012                           tac_plus.conf(5)