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