Please, could someone take a look at this possible conntrack issue? Even just acknowledging that it's reproducible on a selection of recent kernels or architectures would help? Thanks Ed W >> Essentially we have a reproducible situation where conntrack is >> (apparently) relating a packet to a connection, but not incrementing the >> connection counters? >> >> Thanks for any help figuring out a fix? >> >> Ed W >> >> >> On 15/07/2011 12:45, Ed W wrote: >>> Hi, This is related to a previous thread, but more complete problem >>> statement below: >>> >>> I notice that I can get an ICMP packet to bypass parts of conntrack >>> under the following conditions >>> >>> - Send a UDP packet that triggers some kind of UDP reply >>> - Close the listening UDP socket before that reply arrives >>> - Kernel generates an ICMP unreachable response which does not appear to >>> be tracked (as expected) by conntrack >>> >>> Tested with kernel 2.6.38.4 + iptables 1.4.11.1 >>> >>> Reproduce this easily like so: >>> >>> nslookup www.yahoo.co.uk 8.8.8.8 & sleep 0.001 && killall nslookup >>> >>> (where the sleep obviously needs to be smaller than your DNS RTT >>> lookup time. Obviously substitute nslookup/dig as appropriate...) >>> >>> My results >>> >>> # conntrack -E >>> >>> [NEW] udp 17 30 src=10.141.86.7 dst=8.8.8.8 sport=60721 >>> dport=53 [UNREPLIED] src=8.8.8.8 dst=10.141.86.7 sport=53 dport=60721 >>> [UPDATE] udp 17 29 src=10.141.86.7 dst=8.8.8.8 sport=60721 >>> dport=53 src=8.8.8.8 dst=10.141.86.7 sport=53 dport=60721 >>> [DESTROY] udp 17 src=10.141.86.7 dst=8.8.8.8 sport=60721 dport=53 >>> packets=1 bytes=66 src=8.8.8.8 dst=10.141.86.7 sport=53 dport=60721 >>> packets=1 bytes=110 >>> >>> # tcpdump >>> >>> 11:26:35.072564 IP 10.141.86.7.60721 > 8.8.8.8.domain: 2+ PTR? >>> 8.8.8.8.in-addr.arpa. (38) >>> 11:26:35.351804 IP 8.8.8.8.domain > 10.141.86.7.60721: 2 1/0/0 PTR >>> google-public-dns-a.google.com. (82) >>> 11:26:35.352110 IP 10.141.86.7 > 8.8.8.8: ICMP 10.141.86.7 udp port >>> 60721 unreachable, length 118 >>> >>> >>> # iptables -A OUTPUT -j LOGMARK >>> # iptables -A OUTPUT -j LOG >>> >>> Jul 15 11:26:35 localhost kern.warn kernel: [ 6676.964396] iif=0 >>> hook=OUTPUT nfmark=0x0 secmark=0x0 classify=0x0 ctdir=ORIGINAL >>> ct=0xcf3d5060 ctmark=0x0 ctstate=NEW ctstatus= lifetime=6346s >>> Jul 15 11:26:35 localhost kern.warn kernel: [ 6676.964396] IN= OUT=ppp1 >>> SRC=10.141.86.7 DST=8.8.8.8 LEN=66 TOS=0x00 PREC=0x00 TTL=64 ID=19971 DF >>> PROTO=UDP SPT=60721 DPT=53 LEN=46 >>> Jul 15 11:26:35 localhost kern.warn kernel: [ 6677.249312] iif=0 >>> hook=OUTPUT nfmark=0x0 secmark=0x0 classify=0x0 ctdir=ORIGINAL >>> ct=0xcf3d5060 ctmark=0x0 ctstate=RELATED ctstatus=SEEN_REPLY,CONFIRMED >>> lifetime=4294937s >>> Jul 15 11:26:35 localhost kern.warn kernel: [ 6677.249426] IN= OUT=ppp1 >>> SRC=10.141.86.7 DST=8.8.8.8 LEN=138 TOS=0x00 PREC=0xC0 TTL=64 ID=18412 >>> PROTO=ICMP TYPE=3 CODE=3 [SRC=8.8.8.8 DST=10.141.86.7 LEN=110 TOS=0x00 >>> PREC=0x00 TTL=46 ID=3897 PROTO=UDP SPT=53 DPT=60721 LEN=90 >>> >>> >>> Notice that logmark seems to show that the ctstatus on the ICMP packet >>> is SEEN_REPLY, but conntrack -E shows only packets=1? tcpdump shows >>> that the ICMP packet did indeed go out >>> >>> Could someone with more knowledge of conntrack please investigate further? >>> >>> Thanks >>> >>> Ed W >>> -- >>> To unsubscribe from this list: send the line "unsubscribe netfilter" in >>> the body of a message to majordomo@xxxxxxxxxxxxxxx >>> More majordomo info at http://vger.kernel.org/majordomo-info.html >> >> -- >> To unsubscribe from this list: send the line "unsubscribe netfilter" in >> the body of a message to majordomo@xxxxxxxxxxxxxxx >> More majordomo info at http://vger.kernel.org/majordomo-info.html >> > > -- > To unsubscribe from this list: send the line "unsubscribe netfilter-devel" in > the body of a message to majordomo@xxxxxxxxxxxxxxx > More majordomo info at http://vger.kernel.org/majordomo-info.html -- To unsubscribe from this list: send the line "unsubscribe netfilter-devel" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
