Configuring the Serial Line Internet Protocol (SLIP)

Administering SLIP

The slattach(1Mtcp) command establishes a connection over a pre-defined SLIP link. Each time slattach is executed, a new slattach process is created to control the additional SLIP link in use. slattach creates a network interface based on the local and remote IP addresses that are passed to it as parameters.

Parameters to the slattach command define:

the serial communication path for a link by specifying either a tty device or a UUCP site name (the latter requires the -d option)
an IP address for the local side of the communication path and an IP address for the remote side of the communication path
other IP and serial line attributes for the link

Multiple applications (or multiple instances of the same application) on a local host can communicate with the same remote host using the same SLIP link. Use of the same SLIP link requires only that the applications use the same IP address to specify the remote host. By using different IP addresses to specify the same remote host, two applications can also use individual SLIP links to the same host, provided a separate SLIP link exists for each remote IP address.

Once a SLIP link is established, it remains active until:

you mark the associated SLIP interface down using ifconfig(1Mtcp). For example, the command to mark the first SLIP interface down would be:

ifconfig sl0 down

CAUTION: Marking an interface down using ifconfig does not remove the link. Therefore, marking down the interface for an outgoing link that uses a modem and telephone line does not hang up the line. The costs of the line usage continue until the link is removed.
you kill the associated slattach process to remove the SLIP interface.

Once a link has been removed, you may need to remove the associated route from the routing table using the route(1Mtcp) command:

route delete destination_address gateway_address

This should only be necessary if the system is not running a routing daemon such as routed(1Mtcp).