On Tue, Jun 26, 2001 at 02:28:51PM +0530, VaibhaV wrote:
> > How do I decide which network interface to send the packet to depending on
> > whether it is a mail or another protocol packet?
>
> What you are talking about is "protocol based routing / filtering" which
> can be done by using iptables. Search for iptables docs on google.
>
> VaibhaV
To add more to this, see the following link
http://www.ibiblio.org/pub/Linux/docs/HOWTO/other-formats/html_single/Adv-Routing-HOWTO.html#ss8.5
An extract from the relevant section -
================================================
10. Netfilter & iproute - marking packets
So far we've seen how iproute works, and netfilter was mentioned a few
times. This would be a good time to browse through Rusty's Remarkably
Unreliable Guides. Netfilter itself can
be found here.
Netfilter allows us to filter packets, or mangle their headers. One
special feature is that we can mark a packet with a number. This is done
with the --set-mark facility.
As an example, this command marks all packets destined for port 25,
outgoing mail:
# iptables -A PREROUTING -i eth0 -t mangle -p tcp --dport 25 \
-j MARK --set-mark 1
Let's say that we have multiple connections, one that is fast (and
expensive, per megabyte) and one that is slower, but flat fee. We would
most certainly like outgoing mail to go via the
cheap route.
We've already marked the packets with a '1', we now instruct the routing
policy database to act on this:
# echo 201 mail.out >> /etc/iproute2/rt_tables
# ip rule add fwmark 1 table mail.out
# ip rule ls
0: from all lookup local
32764: from all fwmark 1 lookup mail.out
32766: from all lookup main
32767: from all lookup default
Now we generate the mail.out table with a route to the slow but cheap
link:
# /sbin/ip route add default via 195.96.98.253 dev ppp0 table
mail.out
================================================
--
Politicians and Diapers need to be changed often,
and for the same reason.
----------------------------------------------------------
VaibhaV Sharma | [EMAIL PROTECTED]
Exocore Consulting | http://www.exocore.com
Bangalore, India | +91 (80) 3440397
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