I have been seeing some occasional strange behavior when using proxy_arp. I have a router running with an ADSL PPPoE link to the Internet, and an Ethernet link to a local network. It has proxy_arp enabled on the internal Ethernet port since I sometimes have ipsec tunnels running where I use proxy_arp to proxy for the IP assigned to the other end of the tunnel so that local machines can find and reach it. I run two independent subnets on the local network (one with fixed IPs for my machines here, and another with DHCP addresses for guest machines that visit occasionally just to give them Internet access).
I run 10.0.0.0/8 and 192.168.254.0/24 on the local network with the router having an IP in each subnet. The strangeness that occurs is that once in a while there is a 10 second period where the system will answer all arp requests for all IPs on the local network, with it's own MAC address, which is clearly wrong since it doesn't have any of those IP addresses. It seems to happen every couple of days or so on average, although not at any specific time. One day it happened at 11:32:30 to 11:32:39, and a few days later it happened at 12:08:38 to 12:08:48. If I disable proxy_arp, it never happens at all, but then I loose the ability to do what I have proxy_arp enabled for in the first place. Related to that problem, there is also the annoyance that any IP that isn't part of either of the two subnets the router belongs to, have arp requests answered by the router all the time, which it also should not be answering, since it doesn't actually have a clue what those IP addresses belong to and certainly has no idea where it should forward to to reach them. I occasionally have other random subnets in use on the network for running local test networks separate from everything else. It would be great if the kernel would keep its nose out of those subnets too. So far I have seen this behavior with 2.6.8, 2.6.16, and 2.6.18 (being the kernels I have run on this router). So have I misunderstood something about what proxy_arp is supposed to do, or is proxy_arp in the kernel simply broken, or is it perhaps mis-designed? Are there some tuning parameters that could perhaps make it actually do what one would expect it to be doing? -- Len Sorensen - To unsubscribe from this list: send the line "unsubscribe netdev" in the body of a message to [EMAIL PROTECTED] More majordomo info at http://vger.kernel.org/majordomo-info.html
