[Techtalk] no gateway, yet it works!

[Maria Blackmore]

On Thu, 12 Sep 2002, Meredydd Luff wrote:
> Ooh, never heard of that. Sounds like an interesting idea, although a 
> DHCP-handed-out gateway seems like a better idea to me. Could you give a link 
> for a bit more information (eg how to set a machine up to do it, if indeed it 
> can be done without specialised hardware)?

Hi

under linux, as root

echo 1 > /proc/sys/net/ipv4/conf/eth0/proxy_arp

:)

replacing eth0 with whatever ethernet interface, as appropriate

on a cisco router, enable, then do

conf t
int eth0
ip proxy-arp
^Z

once again replacing eth0 with the appropriate interface.

On the client machines on the network simple tell them that the whole
internet is reachable on the local network (network mask 0.0.0.0)

the things doing the routing will need to have a properly and fully
configured routing table so that it knows that the client machines can be
reached out of a particular interface

please remember that by doing this you will get an entry in your ARP table
for every single host that is visited.  Frequently there is a limit on the
size of an ARP table, when it is reached some things will handle it more
gracefully than others.  Cisco kit has a tendancy to simply reload itself
in this situation, others might age out ARP table entries more quickly.

I would always recommend setting up routing and networks explicitly unless
you have some urgent requirement for the flexibility it can give.
DHCP will frequently give a better solution, imho.


Maria