kern/137317: logs full of syncache problems

[kause lotski]

>Number:         137317
>Category:       kern
>Synopsis:       logs full of syncache problems
>Confidential:   no
>Severity:       non-critical
>Priority:       low
>Responsible:    freebsd-bugs
>State:          open
>Quarter:        
>Keywords:       
>Date-Required:
>Class:          sw-bug
>Submitter-Id:   current-users
>Arrival-Date:   Fri Jul 31 22:20:03 UTC 2009
>Closed-Date:
>Last-Modified:
>Originator:     kause lotski
>Release:        7.2. p1
>Organization:
>Environment:
my.domain 7.2-RELEASE-p1 FreeBSD 7.2-RELEASE-p1 #1: Sat Jun 27 00:09:26 CEST 2009     root at server.domaibn:/usr/obj/usr/src/sys/KAUSKERNEL  i386
>Description:
My logs are beeind flooded with messages like this:

Jul 31 23:58:00 premetenec kernel: TCP: [213.253.92.100]:11711 to [xxxxxxxx]:80 tcpflags 0x11<FIN,ACK>; syncache_expand: Segment failed SYNCOOKIE authentication, segment rejected (probably spoofed)
Aug  1 00:00:37 premetenec kernel: TCP: [213.253.92.100]:30837 to [xxxxxxxx]:80 tcpflags 0x11<FIN,ACK>; syncache_expand: Segment failed SYNCOOKIE authentication, segment rejected (probably spoofed)
Aug  1 00:00:41 premetenec kernel: TCP: [83.218.196.142]:1579 to [xxxxxxxx]:25 tcpflags 0x4<RST>; syncache_chkrst: Spurious RST without matching syncache entry (possibly syncookie only), segment ignored
Aug  1 00:00:52 premetenec kernel: TCP: [193.198.80.29]:2524 to [xxxxxxxx]:80 tcpflags 0x2<SYN>; _syncache_add: Received duplicate SYN, resetting timer and retransmitting SYN|ACK
Aug  1 00:01:01 premetenec kernel: TCP: [190.109.157.30]:15396 to [91.185.206.35]:25 tcpflags 0x10<ACK>; syncache_expand: Segment failed SYNCOOKIE authentication, segment rejected (probably spoofed)
Aug  1 00:01:01 premetenec kernel: TCP: [xxxxxxxx]:3353 to [xxxxxxxx]:995 tcpflags 0x4<RST>; syncache_chkrst: Spurious RST without matching syncache entry (possibly syncookie only), segment ignored
Aug  1 00:01:05 premetenec kernel: TCP: [213.253.92.100]:12391 to [xxxxxxxx]:80 tcpflags 0x11<FIN,ACK>; syncache_expand: Segment failed SYNCOOKIE authentication, segment rejected (probably spoofed)
Aug  1 00:02:55 premetenec kernel: TCP: [213.253.92.100]:9833 to [xxxxxxxx]:80 tcpflags 0x11<FIN,ACK>; syncache_expand: Segment failed SYNCOOKIE authentication, segment rejected (probably spoofed)
Aug  1 00:03:54 premetenec kernel: TCP: [213.253.92.100]:6298 to [xxxxxxxx]:80 tcpflags 0x11<FIN,ACK>; syncache_expand: Segment failed SYNCOOKIE authentication, segment rejected (probably spoofed)

Among ip's that are creating this are: my ip, servers own ip, and google! Nearly all messages are apache or pop3-ssl related.

sysctl net.inet.tcp.log_debug=0 does nothing. 
>How-To-Repeat:

>Fix:


>Release-Note:
>Audit-Trail:
>Unformatted: