Date: Fri, 04 Apr 2008 01:34:07 +0200 From: Ivan Voras <ivoras@freebsd.org> To: freebsd-net@freebsd.org Subject: Trouble with IPFW or TCP? Message-ID: <ft3phn$ai3$1@ger.gmane.org>
next in thread | raw e-mail | index | archive | help
[-- Attachment #1 --] In which case would an ipfw ruleset like this: 00100 114872026 40487887607 allow ip from any to any via lo0 00200 0 0 deny ip from any to 127.0.0.0/8 00300 0 0 deny ip from 127.0.0.0/8 to any 00600 1585 112576 deny ip from table(0) to me 01000 90279 7325972 allow icmp from any to any 05000 475961039 334422494257 allow tcp from me to any setup keep-state 05100 634155 65779377 allow udp from me to any keep-state 06022 409604 69177326 allow tcp from any to me dst-port 22 setup keep-state 06080 52159025 43182548092 allow tcp from any to me dst-port 80 setup keep-state 06443 6392366 2043532158 allow tcp from any to me dst-port 443 setup keep-state 07020 517065 292377553 allow tcp from any to me dst-port 8080 setup keep-state 65400 12273387 629703212 deny log ip from any to any 65535 0 0 deny ip from any to any Generate syslog messages like these: Apr 4 01:02:06 my.ip kernel: ipfw: 65400 Deny TCP xx.xx.xx.xx:60725 my.ip.my.ip:443 in via em0 Apr 4 01:02:06 my.ip kernel: ipfw: 65400 Deny TCP xx.xx.xx.xx:57387 my.ip.my.ip:443 in via em0 Apr 4 01:02:06 my.ip kernel: ipfw: 65400 Deny TCP xx.xx.xx.xx:57387 my.ip.my.ip:443 in via em0 Apr 4 01:02:06 my.ip kernel: ipfw: 65400 Deny TCP xx.xx.xx.xx:61998 my.ip.my.ip:443 in via em0 Apr 4 01:02:06 my.ip kernel: ipfw: 65400 Deny TCP xx.xx.xx.xx:61998 my.ip.my.ip:443 in via em0 Apr 4 01:02:06 my.ip kernel: ipfw: 65400 Deny TCP xx.xx.xx.xx:64288 my.ip.my.ip:443 in via em0 Apr 4 01:02:06 my.ip kernel: ipfw: 65400 Deny TCP xx.xx.xx.xx:64288 my.ip.my.ip:443 in via em0 Apr 4 01:02:06 my.ip kernel: ipfw: 65400 Deny TCP xx.xx.xx.xx:50212 my.ip.my.ip:443 in via em0 Apr 4 01:02:06 my.ip kernel: ipfw: 65400 Deny TCP xx.xx.xx.xx:50212 my.ip.my.ip:443 in via em0 Apr 4 01:02:06 my.ip kernel: ipfw: 65400 Deny TCP xx.xx.xx.xx:58149 my.ip.my.ip:443 in via em0 Apr 4 01:02:06 my.ip kernel: ipfw: 65400 Deny TCP xx.xx.xx.xx:58149 my.ip.my.ip:443 in via em0 Apr 4 01:02:13 my.ip kernel: ipfw: 65400 Deny TCP yy.yy.yy.yy:61919 my.ip.my.ip:443 in via em0 Apr 4 01:02:13 my.ip kernel: ipfw: 65400 Deny TCP yy.yy.yy.yy:61919 my.ip.my.ip:443 in via em0 Apr 4 01:02:13 my.ip kernel: ipfw: 65400 Deny TCP yy.yy.yy.yy:56792 my.ip.my.ip:443 in via em0 Apr 4 01:02:13 my.ip kernel: ipfw: 65400 Deny TCP yy.yy.yy.yy:56792 my.ip.my.ip:443 in via em0 Apr 4 01:02:14 my.ip kernel: ipfw: 65400 Deny TCP yy.yy.yy.yy:53795 my.ip.my.ip:443 in via em0 Apr 4 01:02:16 my.ip kernel: ipfw: 65400 Deny TCP zz.zz.zz.zz:58314 my.ip.my.ip:443 in via em0 Apr 4 01:02:16 my.ip kernel: ipfw: 65400 Deny TCP zz.zz.zz.zz:63204 my.ip.my.ip:443 in via em0 Apr 4 01:02:16 my.ip kernel: ipfw: 65400 Deny TCP zz.zz.zz.zz:58314 my.ip.my.ip:443 in via em0 Apr 4 01:02:16 my.ip kernel: ipfw: 65400 Deny TCP zz.zz.zz.zz:52125 my.ip.my.ip:443 in via em0 Apr 4 01:02:16 my.ip kernel: ipfw: 65400 Deny TCP zz.zz.zz.zz:53386 my.ip.my.ip:443 in via em0 Apr 4 01:02:16 my.ip kernel: ipfw: 65400 Deny TCP zz.zz.zz.zz:63626 my.ip.my.ip:443 in via em0 Apr 4 01:02:16 my.ip kernel: ipfw: 65400 Deny TCP zz.zz.zz.zz:63204 my.ip.my.ip:443 in via em0 Apr 4 01:02:16 my.ip kernel: ipfw: 65400 Deny TCP zz.zz.zz.zz:51376 my.ip.my.ip:443 in via em0 Apr 4 01:02:16 my.ip kernel: ipfw: 65400 Deny TCP zz.zz.zz.zz:61880 my.ip.my.ip:443 in via em0 Apr 4 01:02:16 my.ip kernel: ipfw: 65400 Deny TCP zz.zz.zz.zz:49319 my.ip.my.ip:443 in via em0 Apr 4 01:02:16 my.ip kernel: ipfw: 65400 Deny TCP zz.zz.zz.zz:52125 my.ip.my.ip:443 in via em0 Apr 4 01:02:16 my.ip kernel: ipfw: 65400 Deny TCP zz.zz.zz.zz:62381 my.ip.my.ip:443 in via em0 Apr 4 01:02:16 my.ip kernel: ipfw: 65400 Deny TCP zz.zz.zz.zz:53386 my.ip.my.ip:443 in via em0 Apr 4 01:02:16 my.ip kernel: ipfw: 65400 Deny TCP zz.zz.zz.zz:63626 my.ip.my.ip:443 in via em0 Apr 4 01:02:16 my.ip kernel: ipfw: 65400 Deny TCP zz.zz.zz.zz:51376 my.ip.my.ip:443 in via em0 Apr 4 01:02:16 my.ip kernel: ipfw: 65400 Deny TCP zz.zz.zz.zz:54109 my.ip.my.ip:443 in via em0 Apr 4 01:02:16 my.ip kernel: ipfw: 65400 Deny TCP zz.zz.zz.zz:56945 my.ip.my.ip:443 in via em0 Apr 4 01:02:16 my.ip kernel: ipfw: 65400 Deny TCP zz.zz.zz.zz:61880 my.ip.my.ip:443 in via em0 Apr 4 01:02:16 my.ip kernel: ipfw: 65400 Deny TCP zz.zz.zz.zz:50800 my.ip.my.ip:443 in via em0 Apr 4 01:02:16 my.ip kernel: ipfw: 65400 Deny TCP zz.zz.zz.zz:49319 my.ip.my.ip:443 in via em0 Apr 4 01:02:16 my.ip kernel: ipfw: 65400 Deny TCP zz.zz.zz.zz:53347 my.ip.my.ip:443 in via em0 Apr 4 01:02:16 my.ip kernel: ipfw: 65400 Deny TCP zz.zz.zz.zz:58735 my.ip.my.ip:443 in via em0 Apr 4 01:02:16 my.ip kernel: ipfw: 65400 Deny TCP zz.zz.zz.zz:58732 my.ip.my.ip:443 in via em0 Apr 4 01:02:16 my.ip kernel: ipfw: 65400 Deny TCP zz.zz.zz.zz:62381 my.ip.my.ip:443 in via em0 Apr 4 01:02:16 my.ip kernel: ipfw: 65400 Deny TCP zz.zz.zz.zz:56837 my.ip.my.ip:443 in via em0 Apr 4 01:02:16 my.ip kernel: ipfw: 65400 Deny TCP zz.zz.zz.zz:54109 my.ip.my.ip:443 in via em0 Apr 4 01:02:16 my.ip kernel: ipfw: 65400 Deny TCP zz.zz.zz.zz:65318 my.ip.my.ip:443 in via em0 Apr 4 01:02:16 my.ip kernel: ipfw: 65400 Deny TCP zz.zz.zz.zz:56945 my.ip.my.ip:443 in via em0 Apr 4 01:02:16 my.ip kernel: ipfw: 65400 Deny TCP zz.zz.zz.zz:50800 my.ip.my.ip:443 in via em0 Apr 4 01:02:16 my.ip kernel: ipfw: 65400 Deny TCP zz.zz.zz.zz:53347 my.ip.my.ip:443 in via em0 Apr 4 01:02:16 my.ip kernel: ipfw: 65400 Deny TCP zz.zz.zz.zz:58735 my.ip.my.ip:443 in via em0 Apr 4 01:02:16 my.ip kernel: ipfw: 65400 Deny TCP zz.zz.zz.zz:58732 my.ip.my.ip:443 in via em0 Apr 4 01:02:16 my.ip kernel: ipfw: 65400 Deny TCP zz.zz.zz.zz:56837 my.ip.my.ip:443 in via em0 Apr 4 01:02:16 my.ip kernel: ipfw: 65400 Deny TCP zz.zz.zz.zz:65318 my.ip.my.ip:443 in via em0 ? I can connect with plain telnet from the reported addresses without problems. One thing that is suspicious is that the messages come in these bursts (which I can't explain) but the Apache's listen backlog should handle those. In any case, I don't think they are connection requests: Here's output of "tcpdump -v host xx.xx.xx.xx and port 443": 01:13:07.654677 IP (tos 0x0, ttl 58, id 54089, offset 0, flags [none], proto TCP (6), length 40) xx.xx.xx.xx.58789 > my.ip.my.ip.https: ., cksum 0x54ca (correct), ack 3708282724 win 0 01:13:07.654764 IP (tos 0x0, ttl 58, id 54095, offset 0, flags [none], proto TCP (6), length 40) xx.xx.xx.xx.61579 > my.ip.my.ip.https: ., cksum 0xf60d (correct), ack 610863831 win 0 01:13:07.654810 IP (tos 0x0, ttl 58, id 54099, offset 0, flags [none], proto TCP (6), length 40) xx.xx.xx.xx.61852 > my.ip.my.ip.https: ., cksum 0xab18 (correct), ack 1491048554 win 0 01:13:07.654854 IP (tos 0x0, ttl 58, id 54103, offset 0, flags [none], proto TCP (6), length 40) xx.xx.xx.xx.63950 > my.ip.my.ip.https: ., cksum 0x1e51 (correct), ack 2955921131 win 0 01:13:07.654897 IP (tos 0x0, ttl 58, id 54107, offset 0, flags [none], proto TCP (6), length 40) xx.xx.xx.xx.53299 > my.ip.my.ip.https: ., cksum 0xa141 (correct), ack 2339864417 win 0 01:13:07.654940 IP (tos 0x0, ttl 58, id 54121, offset 0, flags [none], proto TCP (6), length 40) xx.xx.xx.xx.50521 > my.ip.my.ip.https: ., cksum 0x2c55 (correct), ack 216576745 win 0 01:13:07.654984 IP (tos 0x0, ttl 58, id 54123, offset 0, flags [DF], proto TCP (6), length 52) xx.xx.xx.xx.58789 > my.ip.my.ip.https: ., cksum 0x882d (correct), ack 1 win 33304 <nop,nop,timestamp 140692997 4077078528> 01:13:07.655026 IP (tos 0x0, ttl 58, id 54126, offset 0, flags [DF], proto TCP (6), length 52) xx.xx.xx.xx.61579 > my.ip.my.ip.https: ., cksum 0x0617 (correct), ack 1 win 33304 <nop,nop,timestamp 140692997 3172245833> 01:13:07.655069 IP (tos 0x0, ttl 58, id 54128, offset 0, flags [DF], proto TCP (6), length 52) xx.xx.xx.xx.61852 > my.ip.my.ip.https: ., cksum 0x7006 (correct), ack 1 win 33304 <nop,nop,timestamp 140692997 3472415360> 01:13:07.655112 IP (tos 0x0, ttl 58, id 54130, offset 0, flags [DF], proto TCP (6), length 52) xx.xx.xx.xx.63950 > my.ip.my.ip.https: ., cksum 0x7ade (correct), ack 1 win 33304 <nop,nop,timestamp 140692997 415365400> 01:13:07.655155 IP (tos 0x0, ttl 58, id 54132, offset 0, flags [DF], proto TCP (6), length 52) xx.xx.xx.xx.53299 > my.ip.my.ip.https: ., cksum 0x4087 (correct), ack 1 win 33304 <nop,nop,timestamp 140692997 2999393370> 01:13:07.655197 IP (tos 0x0, ttl 58, id 54139, offset 0, flags [DF], proto TCP (6), length 52) xx.xx.xx.xx.50521 > my.ip.my.ip.https: ., cksum 0x13e0 (correct), ack 1 win 33304 <nop,nop,timestamp 140692997 3427580559> There are no SYNs here, so it looks to me like something mid-traffic. For addresses such as those in the ipfw log, I see several messages like: Mar 24 17:00:01 my.ip kernel: TCP: [xx.xx.xx.xx]:64714 to [my.ip.my.ip]:443 tcpflags 0x18<PUSH,ACK>; tcp_do_segment: FIN_WAIT_2: Received 198 bytes of data after socket was closed, sending RST and removing tcpcb Mar 24 17:10:57 my.ip kernel: 6110>ipfw: 65400 Deny TCP xx.xx.xx.xx:58213 my.ip.my.ip:443 in via em0 Mar 25 00:00:05 my.ip kernel: TCP: [xx.xx.xx.xx]:52233 to [my.ip.my.ip]:443 tcpflags 0x10<ACK>; syncache_expand: Segment failed SYNCOOKIE authentication, segment rejected (probably spoofed) Mar 25 01:45:05 my.ip kernel: TCP: [xx.xx.xx.xx]:51120 to [my.ip.my.ip]:443 tcpflags 0x10<ACK>; syncache_expand: Segment failed SYNCOOKIE authentication, segment rejected (probably spoofed) Mar 25 01:45:05 my.ip kernel: TCP: [xx.xx.xx.xx]:51120 to [my.ip.my.ip]:443 tcpflags 0x10<ACK>; syncache_expand: Segment failed SYNCOOKIE authentication, segment rejected (probably spoofed) Mar 25 14:00:09 my.ip kernel: TCP: [xx.xx.xx.xx]:55665 to [my.ip.my.ip]:443 tcpflags 0x10<ACK>; syncache_expand: Segment failed SYNCOOKIE authentication, segment rejected (probably spoofed) Mar 25 14:00:09 my.ip kernel: TCP: [xx.xx.xx.xx]:55665 to [my.ip.my.ip]:443 tcpflags 0x10<ACK>; syncache_expand: Segment failed SYNCOOKIE authentication, segment rejected (probably spoofed) Mar 25 17:00:00 my.ip kernel: TCP: [xx.xx.xx.xx]:60048 to [my.ip.my.ip]:443 tcpflags 0x18<PUSH,ACK>; tcp_do_segment: FIN_WAIT_1: Received 346 bytes of data after socket was closed, sending RST and removing tcpcb Mar 25 17:00:00 my.ip kernel: TCP: [xx.xx.xx.xx]:60048 to [my.ip.my.ip]:443 tcpflags 0x11<FIN,ACK>; syncache_expand: Segment failed SYNCOOKIE authentication, segment rejected (probably spoofed) Mar 25 23:00:01 my.ip kernel: TCP: [xx.xx.xx.xx]:50205 to [my.ip.my.ip]:443 tcpflags 0x18<PUSH,ACK>; tcp_do_segment: FIN_WAIT_1: Received 346 bytes of data after socket was closed, sending RST and removing tcpcb Mar 25 23:00:01 my.ip kernel: TCP: [xx.xx.xx.xx]:50205 to [my.ip.my.ip]:443 tcpflags 0x11<FIN,ACK>; syncache_expand: Segment failed SYNCOOKIE authentication, segment rejected (probably spoofed) Mar 26 00:38:49 my.ip kernel: <a10>ipfw: 65400 Deny TCP xx.xx.xx.xx:61129 my.ip.my.ip:443 in via em0 Apr 2 09:00:01 my.ip kernel: TCP: [xx.xx.xx.xx]:57248 to [my.ip.my.ip]:443 tcpflags 0x18<PUSH,ACK>; tcp_do_segment: FIN_WAIT_1: Received 330 bytes of data after socket was closed, sending RST and removing tcpcb Apr 2 09:00:01 my.ip kernel: TCP: [xx.xx.xx.xx]:57248 to [my.ip.my.ip]:443 tcpflags 0x11<FIN,ACK>; syncache_expand: Segment failed SYNCOOKIE authentication, segment rejected (probably spoofed) But these messages do *not* occur when the ipfw log and tcpdump record the above described behaviour so it might not be connected. The machine at my.ip is running 7.0-RELEASE i386, the rest are a set of machines that send trivial periodic (every 15 minutes) HTTPS messages to this machine. In this set most are 6.2 or 6.3, mixed i386 and amd64. The one 7-STABLE machine that does the same thing doesn't generate the behaviour described above so it might be something specific to when 6.x machines talk to 7.x. Was there a bug like that in 6.x? [-- Attachment #2 --] -----BEGIN PGP SIGNATURE----- Version: GnuPG v1.2.5 (MingW32) Comment: Using GnuPG with Mozilla - http://enigmail.mozdev.org iD8DBQFH9Wl1ldnAQVacBcgRAnwfAJ9jkCiQbHFCari7u2iR/FseGAlbeQCfSF7y RpnNQrpzFeYeXTGhcg6UBGg= =WLHk -----END PGP SIGNATURE-----
Want to link to this message? Use this URL: <https://mail-archive.FreeBSD.org/cgi/mid.cgi?ft3phn$ai3$1>