Problem with closing tcp session between cisco and freebsd

[Andre Oppermann]

Zherdev Anatoly wrote:
> 
> Hello.
> 
> I have problem with tcp session close between cisco and freebsd
> Looks like that it bug in freebsd tcp stack.

What version of FreeBSD and Cisco IOS do you run on these machines?

-- 
Andre


> CISCO state:
> 
> sh tcp brief
> 62935208  CISCO..990    FREEBSD.513 FINWAIT1
> 
> FreeBSD state:
> 
> netstat -an
> tcp4   57352      0  FREEBSD.513        CISCO.990       ESTABLISHED
> 
> TCP session from cisco side:
> 
> IP: s=CISCO (local), d=FREEBSD (FastEthernet0), len 41,
> sending TCP src=990, dst=513, seq=1411875745, ack=880111139, win=3983 ACK
> PSH FIN
> 
> IP: s=FREEBSD (FastEthernet0), d=CISCO (FastEthernet0), len
> 40, rcvd 3 TCP src=513, dst=990, seq=880111139, ack=1411875745, win=0 ACK
> 
> IP: s=CISCO (local), d=FREEBSD (FastEthernet0), len 41,
> sending TCP src=990, dst=513, seq=1411875745, ack=880111139, win=3983 ACK
> PSH FIN
> 
> IP: s=FREEBSD (FastEthernet0), d=CISCO (FastEthernet0), len
> 40, rcvd 3 TCP src=513, dst=990, seq=880111139, ack=1411875745, win=0 ACK
> 
> ....
> 
> TCP session from FreeBSD side:
> 
> 12:16:25.426584 IP CISCO.990 > FREEBSD.login: FP 1411875745:1411875746(1) ack 880111139 win 3714
> 
> 12:16:25.426675 IP FREEBSD.login > CISCO.990: . ack 1411875745 win 0
> 
> 12:16:35.121888 IP CISCO.990 > FREEBSD.login: FP 1411875745:1411875746(1) ack 880111139 win 3714
> 
> 12:16:35.121976 IP FREEBSD.login > CISCO.990: . ack 1411875745 win 0
> 
> ....
> 
> CISCO send ACK on FreeBSD pocket and send FIN. FreeBSD send ACK with seq w/o changes win=0 (!) and ack=cisco_seq.Cisco wait ack=cisco_seq+1 on FIN but FreeBSD box don't send this and cisco retransmit FIN.
> 
> --
> Zherdev Anatoly.
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