Linux - NetworkingThis forum is for any issue related to networks or networking.
Routing, network cards, OSI, etc. Anything is fair game.
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I need a little assistance on tracking down a problem with an iptables script i've wrote. It's extremely basic, but doesn't seem to be working. I should note that i am very new to iptables though so i must have something wrong somewhere.
Background:
I'm setting up this box as a qos machine for our network. I will be putting it in between a pix501 and the rest of the network. The pix does our firewalling as well as routing public IP's to our various servers.
I need the qos box to pass all traffic unmodified to the pix so that the ip routing remains unaffected, so no MASQ setups.
pix 172.16.1.1
eth0 LAN : 172.16.1.200
eth1 WAN : 172.16.1.201
I have eth1 connected to the pix while the rest of the network runs into eth0.
Part of this i wrote myself and part of it i took from other examples i found around the net, which could be my issue.
My current routes, this i've been staring at for hours and not sure if i have it right either.
ip route
172.16.1.1 dev eth1 scope link
172.16.0.0/16 dev eth0 proto kernel scope link src 172.16.1.200
127.0.0.0/8 dev lo scope link
default via 172.16.1.1 dev eth1
With this setup i'm able to ping both eth0 and eth1 from the lan side, however i cannot ping the pix. The linux box itself can ping the pix and machines on the lan.
It seems to me if i can ping 172.16.1.201 from the lan side, then part of my routing is working, it's just once it trys to go past eth1 it stops.
I ran a tcpdump when trying to ping the pix and all i would see were arp requests, but no replys.
you have both nic's on the same subnet? that's illegal, doesn't make any sense at all. do you actually want this box to be a transparent bridge? if so, iptales isn't what you're after, but ebtables to do packet filtering on pair of bridged interfaces.
I've setup bridging before and it was working perfectly for routing however it broke my qos script (prometheus) so i was attempting to do it with iptables. But as you can see my knowledge of subnetting isn't quite up to par.
I had never seen ebtables before but based on the link you provided i think i might be able to write up a very basic qos script, instead of using a prepackaged one. Unless you know of any qos scripts based off ebtables because that would make life much easier
Thank you for the suggestions, i think i'll poke around the net some more for info on ebtables and possibly a qos script based on that. If you have anymore suggestions i would love to hear them.
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