From: Chris Friesen <cfriesen@nortelnetworks.com>
To: David Ashley <dash@xdr.com>
Cc: linux-kernel@vger.kernel.org
Subject: Re: Problem in ARP 2.4.20 kernel
Date: Mon, 19 May 2003 20:36:25 -0400 [thread overview]
Message-ID: <3EC97889.6040509@nortelnetworks.com> (raw)
In-Reply-To: 200305162202.h4GM2LGN024925@xdr.com
David Ashley wrote:
> The problem I ran into was the kernel's handling of ARP requests. What linux
> does is each interface receives the arp request, and every single one
> answers the request. So it becomes a race condition which response gets to
> the client, and the client will have usually an incorrect mac address/ip
> address arp entry.
This was hashed through on the list about a year back. You might try googling
next time...
This is actually standards compliant behaviour, as silly as it sounds. However,
if you want stricter arp behaviour, and are using source-based routing, the
following will fix it.
echo 1 > /proc/sys/net/ipv4/conf/all/arp_filter
Here is an example setup on 2.4.18:
# ip add
1: lo: <LOOPBACK,UP> mtu 16436 qdisc noqueue
link/loopback 00:00:00:00:00:00 brd 00:00:00:00:00:00
inet 127.0.0.1/8 brd 127.255.255.255 scope host lo
2: eth0: <BROADCAST,MULTICAST,UP> mtu 1500 qdisc pfifo_fast qlen 100
link/ether 00:30:65:bf:46:ba brd ff:ff:ff:ff:ff:ff
inet 47.129.82.58/24 brd 47.129.82.255 scope global eth0
3: eth1: <BROADCAST,MULTICAST,UP> mtu 1500 qdisc pfifo_fast qlen 100
link/ether 00:50:ff:90:04:44 brd ff:ff:ff:ff:ff:ff
inet 47.129.82.107/24 brd 47.129.82.255 scope global eth1
# ip ru
0: from all lookup local
32764: from 47.129.82.107 lookup 101
32765: from 47.129.82.58 lookup 100
32766: from all lookup main
32767: from all lookup 253
# ip ro
47.129.82.0/24 dev eth0 proto kernel scope link src 47.129.82.58
47.129.82.0/24 dev eth1 proto kernel scope link src 47.129.82.107
127.0.0.0/8 dev lo scope link
default via 47.129.82.1 dev eth0
# ip ro li table 100
47.129.82.0/24 dev eth0 scope link
default via 47.129.82.1 dev eth0
# ip ro li table 101
47.129.82.0/24 dev eth1 scope link
default via 47.129.82.1 dev eth1
With this setup, arp requests for 47.129.82.58 will only be answered by eth0,
and similarly for 47.129.82.107 and eth1.
Chris
--
Chris Friesen | MailStop: 043/33/F10
Nortel Networks | work: (613) 765-0557
3500 Carling Avenue | fax: (613) 765-2986
Nepean, ON K2H 8E9 Canada | email: cfriesen@nortelnetworks.com
prev parent reply other threads:[~2003-05-20 0:23 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2003-05-16 22:02 Problem in ARP 2.4.20 kernel David Ashley
2003-05-16 23:41 ` Robert White
2003-05-20 0:36 ` Chris Friesen [this message]
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