SLIP packet filtering
SLIP permits the transfer of IP packets over a
serial line via a SLIP network interface.
Packet filtering permits control of the traffic through a SLIP
network interface
based on the contents of the packets passed to the interface.
Unlike PPP, which allows ``keep up'' and ``bring up''
filtering as well, SLIP only provides ``pass'' filtering.
By default, any packet passed to an interface is allowed to pass through that interface. Packet filtering provides for specifying that only some types of packet may pass through a SLIP interface.
The following packet content can be used to qualify or disqualify a packet: