Configuring the Serial Line Internet Protocol (SLIP)

Advanced SLIP configuration

Advanced configuration consists of using the Advanced Options or directly editing the slattach entry in /etc/tcp to configure:

Configuring proxy address resolution

To configure proxy address resolution, perform one of these actions:

Configuring TCP/IP header compression

To configure TCP/IP header compression, perform one of these actions:

Configuring flow control

To configure hardware flow control, perform one of these actions:

Configuring ICMP packet suppression

To configure ICMP packet suppression, perform one of these actions:

Configuring the maximum transmission unit

To configure the maximum transmission unit (MTU) for each link, perform one of these actions:

The default MTU value is 296. Increasing this value may increase throughput as packets can contain more data. However, it may also decrease throughput if packets are routed through systems with lower MTU values, as each packet is split (fragmented) into smaller packets for transmittal. You can experiment with this value to obtain the most desirable results.

NOTE: The suggested value for the MTU is 40 plus some power of 2. For example, the default value, 296, is 40 plus 2^8. Other possible values include 552, 1064, and 2088.

Configuring SLIP debugging messages

To configure debugging mode, perform one of these actions:

Configuring packet filtering

To specify a packet filter for a SLIP link:

  1. Create a filter entry in the file /etc/pppfilter. See the packetfilter(SFF) manual page for a description of the format for the filter file.

  2. Perform one of the following actions:

NOTE: Two or more SLIP link configurations may specify the same filter file entry. Also, a SLIP link may share a filter file entry with a PPP link. If the entry contains the bringup or keepup keywords for use in filtering PPP packets, SLIP ignores these parts of the entry.

If /etc/pppfilter does not exist or no filter file entry is specified for a link, then all packets are passed.

Following is an example filter entry:

   # tag      keyword     filter
   sample     pass        !port ntp and !port who and !port timed
The above specification does not allow ntp, who, and timed packets to pass through the network interface. For this packet filter to apply to a SLIP link, the tag ``sample'' must be specified on the slattach command line with the -p option.
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© 2003 Caldera International, Inc. All rights reserved.
SCO OpenServer Release 5.0.7 -- 11 February 2003