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From: Jihoon Chung <difro@sexycoder.com>
To: netfilter@lists.netfilter.org
Subject: udp connection(snmp) not being tracked. probable bug?
Date: Thu, 27 Mar 2003 17:17:59 +0900	[thread overview]
Message-ID: <20030327081759.GA2811@morpheus> (raw)

Using kernel 2.4.20.

I have a netfilter gateway with 2 external ip
eth0: 1.1.1.1 (gw: 1.1.1.254)
eth1: 2.2.2.2 (gw: 2.2.2.254)

It has default route like this

default
	nexthop via 1.1.1.254  dev eth0 weight 1
	nexthop via 2.2.2.254  dev eth1 weight 200

SNMPd is running on the gateway (ucd-snmp).

When I snmp-get to ip 1.1.1.1 (from outside the netfilter gateway, say
3.3.3.3), the reply comes back though eth1 with ip 2.2.2.2

As you can see from what I captured of /proc/net/ip_conntrack, I think
udp packets are not being tracked properly.
(I've modified the ip address accordingly)

-----------------
udp      17 29 src=2.2.2.2 dst=3.3.3.3 sport=161 dport=1914 [UNREPLIED] src=3.3.3.3 dst=2.2.2.2 sport=1914 dport=161 use=1 mark=0 
udp      17 28 src=2.2.2.2 dst=3.3.3.3 sport=161 dport=1913 [UNREPLIED] src=3.3.3.3 dst=2.2.2.2 sport=1913 dport=161 use=1 mark=0 
udp      17 27 src=2.2.2.2 dst=3.3.3.3 sport=161 dport=1912 [UNREPLIED] src=3.3.3.3 dst=2.2.2.2 sport=1912 dport=161 use=1 mark=0 
udp      17 27 src=3.3.3.3 dst=1.1.1.1 sport=1912 dport=161 [UNREPLIED] src=1.1.1.1 dst=3.3.3.3 sport=161 dport=1912 use=1 mark=0 
udp      17 28 src=3.3.3.3 dst=1.1.1.1 sport=1913 dport=161 [UNREPLIED] src=1.1.1.1 dst=3.3.3.3 sport=161 dport=1913 use=1 mark=0 
udp      17 29 src=3.3.3.3 dst=1.1.1.1 sport=1914 dport=161 [UNREPLIED] src=1.1.1.1 dst=3.3.3.3 sport=161 dport=1914 use=1 mark=0 
----------------

I write a small UDP echo server/client and tested it on the gateway.
The result was same:  reply comes out from the wrong interface with
wrong ip.

Is this a known bug?


                 reply	other threads:[~2003-03-27  8:17 UTC|newest]

Thread overview: [no followups] expand[flat|nested]  mbox.gz  Atom feed

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