Re: ARP request bug?
Julian Anastasov <[email protected]>
| Newsgroups | gmane.linux.network.general |
|---|---|
| Message-ID | <[email protected]> |
Hello, On Thu, 17 Feb 2011, Bart Kus wrote: > Hello Experts, > > With 00:04:23:bb:18:56 being a Linux box, it gets a ping request from a > network device: > > 05:50:50.393373 00:0c:db:b5:b7:00 (oui Unknown) > 00:04:23:bb:18:56 (oui > Unknown), ethertype IPv4 (0x0800), length 60: 172.20.11.3 > 192.168.70.1: > ICMP echo request, id 43981, seq 1, length 24 > > Before replying (even though it could, since it has the MAC as part of the > ping request) it decides to query for the MAC based on source IP of the > original ping request: > > 05:50:50.402347 00:04:23:bb:18:56 (oui Unknown) > Broadcast, ethertype ARP > (0x0806), length 42: Request who-has 172.20.11.3 tell 192.168.70.1, length 28 > > The tell section indicates to "tell 192.168.70.1", but the interface on which > this came in has an IP of 172.20.11.1. 192.168.70.1 is another IP on the > Linux router, on a different interface. > > Shouldn't the ARP request say "tell 172.20.11.1" instead given ARP is an > ethernet protocol, incapable of routing to 192.168.70.1? The reply to this > broadcast never comes back from the other network device due to the weird > "tell 192.168.70.1" being there. The end result is complete ping loss. May be what you need is to set on Linux box /proc/.../arp_announce to 1 or 2. Check Documentation/networking/ip-sysctl.txt for more info. Regards -- Julian Anastasov <[email protected]> -- To unsubscribe from this list: send the line "unsubscribe linux-net" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html