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Hi Pandu, |
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thanks for your reply. |
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As far as I can see, proxy_arp is not enabled on any interfaces: |
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host conf # pwd |
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/proc/sys/net/ipv4/conf |
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Host conf # for f in $(find | grep -i proxy_arp | grep -v pvlan ); do echo $f && cat $f ;done |
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./all/proxy_arp |
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0 |
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./default/proxy_arp |
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0 |
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./lo/proxy_arp |
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0 |
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./sit0/proxy_arp |
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0 |
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./lan/proxy_arp |
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0 |
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./dmz/proxy_arp |
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0 |
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./isp/proxy_arp |
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0 |
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./dsl/proxy_arp |
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0 |
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./wlan/proxy_arp |
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0 |
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./mgm/proxy_arp |
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0 |
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./br0/proxy_arp |
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0 |
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./ppp0/proxy_arp |
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0 |
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./tun1/proxy_arp |
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0 |
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./tun0/proxy_arp |
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0 |
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Regards, |
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Ralf |
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Von: Pandu Poluan [mailto:pandu@××××××.info] |
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Gesendet: Mittwoch, 4. Januar 2012 18:29 |
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An: gentoo-user@l.g.o |
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Betreff: Re: [gentoo-user] ARP-Caching of non-link-local adresses |
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On Jan 4, 2012 11:20 PM, "Peter Pan" <osaka@×××.net> wrote: |
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> |
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> Hi list, |
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> |
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> |
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> |
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> I’m kind of despair. |
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> |
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> The history: We recently brought up a new firewall with Gentoo. |
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> |
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> There are (for my finding) some big nets behind this firewall (1x public /24, 2x public /27, 1x public /26, at least 2 private /24). |
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> |
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> Filtering is done via iptables and snort should jump as IPS on software-bridge br0. If it helps: There is also ip rule involved for source-based routing. |
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> |
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> |
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> |
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> The new firewall replaces an older Gentoo-system which did not show this behavior. We therefore copied several configfiles from the old to the new one. |
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> |
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> |
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> |
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> After getting it live, it runs well for a few hours and then becomes unreachable (also for hosts behind the bridge). |
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> |
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> Dmesg / kern.log stated at this time a neighbor table overflow and indeed, arp –n | wc –l showed a lot of entry’s. |
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> As Google suggested, We then adjusted /proc/sys/net/ipv4/neigh/default/ to: |
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> |
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> gc_thershold1 -> 8192 |
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> |
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> gc_thershold2 -> 16384 |
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> |
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> gc_thershold3 -> 32768 |
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> |
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> |
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> Fireing an “arp –d $bogus-ip-adress” is failing with „SIOCDARP(dontpub): Network is unreachable”, adding –i br0 doesn’t fail, but does not remove the line in the arp-table (it only says “incomplete” after greping arp -n again).. |
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> |
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> Therefore we are currently killing the arp-cache with “ip link set arp off dev br0 && ip link set arp on dev br0” by a cronjob. |
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> The combination of these workarounds are keeping the firewall reachable and “alive”. |
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> After stabilizing, we looked at the output of arp –n and noticed, that about 99(.999)% of the roundabout 11.000 (and rising) arp-cache-entry’s contained public addresses for which the bridge of the firewall should not feel responsible (e.g. the public Google-dns-resolver and a load of more). |
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> The MAC-entry for these public addresses is always the one of our router, which is for sure the correct next hop. |
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> But from my understanding, it should arp-cache only “our” net’s directly at the cable and not those public ones. |
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> It looks like a configuration-issue, but I don’t know, where to start looking. I’ve already checked the default-gateway, netmasks, broadcast-addresses and to me, they are looking fine, so any poke where to start looking is greatly appreciated. |
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> In case it will help, I attached the /etc/conf.d/net, ifconfig –a and route -n. |
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> If something else is needed, feel free to ask. |
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> Hope, anyone can help. |
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> |
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Try turning off proxy ARP on the internal and/or external interfaces. |
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Rgds, |
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