Check arp_* fields in https://www.kernel.org/doc/Documentation/networking/ip-sysctl.txt <https://www.kernel.org/doc/Documentation/networking/ip-sysctl.txt>
-daveti > On Jan 19, 2015, at 7:11 PM, Mike Krinkin <[email protected]> wrote: > > Hi, > > On Mon, Jan 19, 2015 at 03:42:58PM -0800, Mandeep Sandhu wrote: >> Hi All, >> >> Please let me know if this is not the correct ML for such a question >> (or if there's a more appropriate list for it). >> >> I'm currently debugging an issue where Linux is not responding to ARP >> requests (testing with custom network interface h/w). >> >> I have 2 network interfaces which are basically interfaces on a custom >> network device sitting on the PCI bus. >> >> My setup looks like follows: >> >> xeth0 - 192.168.2.1 >> xeth2 - 192.168.2.2 >> >> xeth0/2 are the interfaces created for the custom device (via a lkm) >> >> Both these interfaces are on the local machine and are connected >> back-to-back on the custom device, so packets sent from one arrive on >> the other. >> >> I'm testing this setup by sending a single ARP pack, forced out of one >> interface, for the other interface's IP. >> >> $ sudo arping -c 1 -i xeth0 192.168.2.2 >> ARPING 192.168.2.2 >> >> --- 192.168.2.2 statistics --- >> 1 packets transmitted, 0 packets received, 100% unanswered (0 extra) >> >> If I start tcpdump on the receive interface (xeth2), I see the ARP >> packet arrive, but I don't see any response go out (I've attached the >> pcap file for anyone interested in looking at the received packet). >> The ARP packet's contents seem to be proper under wireshark. >> >> Is there any statistics I can look at to see if the packet was dropped >> by linux during ARP processing? >> >> I've put debug stmts in the LKM, but I don't see the kernel IP layer >> calling the xmit function for an ARP reply (however the xmit function >> for the ARP request, from xeth0, is being called). > > Have you tried to put debug prints in arp_process function? > >> >> I don't see any drops in "netstat -s" output as well. >> >> Any hints appreciated. > > Just a random guess, but try to disable reverse path filtering (rp_filter). > >> >> Thanks, >> -mandeep > >> ????w??T?g<<???????~e?~e???? >> _______________________________________________ >> Kernelnewbies mailing list >> [email protected] <mailto:[email protected]> >> http://lists.kernelnewbies.org/mailman/listinfo/kernelnewbies >> <http://lists.kernelnewbies.org/mailman/listinfo/kernelnewbies> > > > _______________________________________________ > Kernelnewbies mailing list > [email protected] <mailto:[email protected]> > http://lists.kernelnewbies.org/mailman/listinfo/kernelnewbies > <http://lists.kernelnewbies.org/mailman/listinfo/kernelnewbies>
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