Messages in this thread | | | Date | Mon, 19 May 2003 20:36:25 -0400 | From | Chris Friesen <> | Subject | Re: Problem in ARP 2.4.20 kernel |
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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
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