Spurious ACKs, ICMP unreachable?

Sat May 14 12:53:10 UTC 2011

Ivan,

I was also going to mention these threads in the previous message to
this list.

This is the thread that ended up getting committed and MFC'd from the
previous mesage.

Feb 08 John Baldwin    (  73) TCP can advertise a really huge window

These is does not seem anything more has happened with them.
Feb 08 John Baldwin    (  88) A small TCP bug: excessive duplicate ACKs
Feb 08 John Baldwin    ( 244) TCP connections stuck inpersist state

On Fri, May 13, 2011 at 04:07:31PM -0400, Ivan Voras wrote:
> I'm seeing an an unusual problem at a remote machine; this machine is
> the FreeBSD server, and the client is a probably Windows machine (but I
> don't know the details yet). Something happens which causes FreeBSD to
> send ACKs to the client, and the client to send ICMP unreachable
> messages to the server. It is most likely a configuration error at the
> remote site but I have no idea how to verify this.
> 
> A tcpdump sample is attached. Any ideas what to look into next?
> 
> 
> 18:56:02.711942 IP server.http > client.4732: Flags [.], ack 2110905191,
> win 0, length 0
> E..(J... at .W..(.d.(.D.P.|....}..gP...lR..
> 18:56:02.712009 IP server.http > client.elan: Flags [.], ack 2661379534,
> win 0, length 0
> E..(J... at .V..(.d.(.D.P.b.(....m.P.......
> 18:56:02.712025 IP server.http > client.2402: Flags [.], ack 2197439003,
> win 0, length 0
> E..(J... at .V..(.d.(.D.P  b.m>5..B.P... at p..
> 18:56:02.712064 IP server.http > client.3427: Flags [.], ack 1373214750,
> win 0, length 0
> E..(K%.. at .V..(.d.(.D.P^Mc_N..Q...P.......
> 18:56:02.712176 IP server.http > client.1893: Flags [.], ack 3549121877,
> win 0, length 0
> E..(K... at .V..(.d.(.D.P.ee..G..MUP...~_..
> 18:56:02.712304 IP server.http > client.atex_elmd: Flags [.], ack
> 2600295677, win 0, length 0
> E..(Lq.. at .UU.(.d.(.D.P.i.*.F..\.P...,...
> 18:56:02.713155 IP server.http > client.4732: Flags [.], ack 1, win
> 65535, length 0
> E..(L. at .@..2.(.d.(.D.P.|....}..gP.......
> 18:56:02.713193 IP server.http > client.elan: Flags [.], ack 1, win
> 65535, length 0
> E..(L. at .@....(.d.(.D.P.b.(....m.P.......
> 18:56:02.713206 IP server.http > client.2402: Flags [.], ack 1, win
> 65535, length 0
> E..(L. at .@....(.d.(.D.P  b.m>6..B.P.......
> 18:56:02.713452 IP server.http > client.3427: Flags [.], ack 1, win
> 65535, length 0
> E..(L. at .@....(.d.(.D.P^Mc_N..Q...P.......
> 18:56:02.713937 IP server.http > client.1893: Flags [.], ack 1, win
> ovd65535, length 0
> E..(M'@. at ....(.d.(.D.P.ee..H..MUP.......
> 18:56:02.714436 IP server.http > client.atex_elmd: Flags [.], ack 1, win
> 65535, length 0
> E..(M. at .@..P.(.d.(.D.P.i.*.G..\.P.......
> 18:56:05.723511 IP client > server: ICMP host client unreachable, length 48
> E..D.8..?....(.D.(.d........E..(J...>.Y..(.d.(.D.P.|....}..gP...lR..
> 18:56:05.723527 IP client > server: ICMP host client unreachable, length 48
> E..D.9..?....(.D.(.d........E..(L. at .>..2.(.d.(.D.P.|....}..gP...lQ..
> 18:56:07.712140 IP server.http > client.1859: Flags [.], ack 70891158,
> win 0, length 0
> E..(N0.. at .S..(.d.(.D.P.C.>S..9..P.......
> 18:56:07.712161 IP server.http > client.dict: Flags [.], ack 878675698,
> win 0, length 0
> E..(NF.. at .S..(.d.(.D.P
> D...:4_..P...g...
> 18:56:07.713390 IP server.http > client.1859: Flags [.], ack 1, win
> 65535, length 0
> E..(O. at .@....(.d.(.D.P.C.>S..9..P.......
> 18:56:07.713459 IP server.http > client.dict: Flags [.], ack 1, win
> 65535, length 0
> E..(O. at .@....(.d.(.D.P
> D...;4_..P.......
> 18:56:17.712207 IP server.http > client.3454: Flags [.], ack 119451926,
> win 0, length 0
> E..(R... at .O..(.d.(.D.P^M~@.i.....P...f7..
> 18:56:17.712354 IP server.http > client.2412: Flags [.], ack 4105579117,
> win 0, length 0
> E..(R... at .N..(.d.(.D.P  l......*mP.......
> 18:56:17.712448 IP server.http > client.3438: Flags [.], ack 1002884906,
> win 0, length 0
> E..(SL.. at .Nz.(.d.(.D.P^MnF.;.;..*P...;...
> 18:56:17.713764 IP server.http > client.3454: Flags [.], ack 1, win
> 65535, length 0
> E..(S. at .@.^M..(.d.(.D.P^M~@.i.....P.......
> 18:56:17.714361 IP server.http > client.2412: Flags [.], ack 1, win
> 65535, length 0
> E..(TY at .@.^M}.(.d.(.D.P l......*mP.......
> 
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-- 

 Regards, (jhell)
 Jason Hellenthal

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