How to enable proxy arp on Linux 2.4

What is proxy arp?

When you turn on proxy arp for a network interface card (nic), then it will answer all arp requests with its own ip-address. What does this mean?

When do you need proxy arp?

Proxy arp is a solution if for some reason you cannot configure a computer or other device on the LAN to use your computer as gateway instead of another one or instead of delivering all packets locally to the LAN.

How is it turned on with Linux?

With one simple command: Let's say your nic is eth1. The command would then be this:

# echo 1 > /proc/sys/net/ipv4/conf/eth1/proxy_arp

Turning it off again is done by:

# echo 0 > /proc/sys/net/ipv4/conf/eth1/proxy_arp

Checking wether it's turned on:

# cat /proc/sys/net/ipv4/conf/eth1/proxy_arp

Keywords: arp proxyarp linux24   Author: Mathias Kettner

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