3.6 TCP Wrappers

Access to servers having addresses in ‘INET’ family is controlled using TCP wrappers⁶.

This system is based on two files, called tables, containing access rules. There are two tables: the allow table, stored in file /etc/hosts.allow, and the deny table, kept in file /etc/hosts.deny. The rules in each table begin with an identifier called daemon name. Access to a Smap server is controlled by two entries: a global one, with the daemon name ‘smapd’, and per-server one, with server ID (see server id as its daemon name. The latter takes precedence over the former. For example, if you have the following in your smapd.conf:

server main inet://192.168.10.1

and wish this server to be accessible only to machines 192.168.10.2 and 192.168.10.3, then you would add the following line to your /etc/hosts.allow:

main: 192.168.10.2 192.168.10.3

and the following line to your /etc/hosts.deny:

main: ALL

The former allows access from these two IPs, and the latter blocks it from any other IPs.

A detailed description of TCP wrapper table format lies outside the scope of this document. Please, see ACCESS CONTROL FILES in hosts_access(5) man page, for details.