tacplus.conf contains the information necessary to configure the TACACS+ client library. It is parsed by tac_config (see libtacplus(3)). The file contains one or more lines of text, each describing a single TACACS+ server which is to be used by the library. Leading white space is ignored, as are empty lines and lines containing only comments.
A TACACS+ server is described by two to four fields on a line. The fields are separated by white space. The # character at the beginning of a field begins a comment, which extends to the end of the line. A field may be enclosed in double quotes, in which case it may contain white space and/or begin with the # character. Within a quoted string, the double quote character can be represented by \", and the backslash can be represented by \\. No other escape sequences are supported.
The first field specifies the server host, either as a fully qualified domain name or as a dotted-quad IP address. The host may optionally be followed by a : and a numeric port number, without intervening white space. If the port specification is omitted, it defaults to 49, the standard TACACS+ port.
The second field contains the shared secret, which should be known only to the client and server hosts. It is an arbitrary string of characters, though it must be enclosed in double quotes if it contains white space or is empty. An empty secret disables the normal encryption mechanism, causing all data to cross the network in cleartext.
The third field contains a decimal integer specifying the timeout in seconds for communicating with the server. The timeout applies separately to each connect, write, and read operation. If this field is omitted, it defaults to 3 seconds.
The optional fourth field may contain the string single-connection. If this option is included, the library will attempt to negotiate with the server to keep the TCP connection open for multiple sessions. Some older TACACS+ servers become confused if this option is specified.
Up to 10 TACACS+ servers may be specified. The servers are tried in order, until a valid response is received or the list is exhausted.
The standard location for this file is /etc/tacplus.conf. An alternate pathname may be specified in the call to tac_config (see libtacplus(3)). Since the file contains sensitive information in the form of the shared secrets, it should not be readable except by root.
# A simple entry using all the defaults:
# A server using a non-standard port, with an increased timeout and
# the "single-connection" option.
auth.domain.com:4333 "Dont tell!!" 15 single-connection
# A server specified by its IP address: