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SubjectRe: Alan's bug catalogue

In article <4ojt5a$qd3@nz12.rz.uni-karlsruhe.de>,
Olaf Erb <erb@inss1.etec.uni-karlsruhe.de> wrote:
>In article <m0uOsZW-0005FrC@lightning.swansea.linux.org.uk>,
>Alan Cox <alan@lxorguk.ukuu.org.uk> wrote:
>>TCP hang 2.0 pre7
>
>Maybe that's the same: sendmail (8.7.5) hangs while connect() with no
>timer running (pre7, 8, 9):
>
>tcp 0 0 myself.uni-karlsruhe.de:1126 blah.de:smtp
>SYN_SENT myself off (0.00/0)
>
>then connect() never fails and sendmail hangs until it's killed.

I've seen sockets that get stuck in this state as well. It doesn't
happen very often for me, but when it happens, the connect also never
finishes without killing the program.

One other problem I have seen at least though 2.0 pre7 was ip
forwarding was still failing for me when the data was over a few K.
Telneting from one linux machine through another linux machine to
a SunOS machine would hang when I tried to display a large amount
of information at once (I run trn, and it hangs trying to display
the screen).

I've done a tcp dump of around the time of the hang, and I'm seeing
lots of acks to the same packet. The connection to the SunOS machine
at netcom is via a SLIP connection.

# tcpdump "host zeego && host netcom10.netcom.com"
<Cut>
19:39:44.509778 netcom10.telnet > zeego.1036: . ack 80 win 16000
19:39:44.529778 netcom10.telnet > zeego.1036: . 1453:1457(4) ack 80 win 16000
19:39:44.689778 zeego.1036 > netcom10.telnet: . ack 1457 win 31744
19:39:44.949778 netcom10.telnet > zeego.1036: . 1457:1526(69) ack 80 win 16000
19:39:45.109778 zeego.1036 > netcom10.telnet: . ack 1526 win 31744
19:39:45.249778 netcom10.telnet > zeego.1036: . 1526:2535(1009) ack 80 win 16000
19:39:45.409778 zeego.1036 > netcom10.telnet: . ack 2535 win 31744
19:39:45.649778 netcom10.telnet > zeego.1036: . 3975:3995(20) ack 80 win 16000
19:39:45.649778 zeego.1036 > netcom10.telnet: . ack 2535 win 31744
19:39:45.709778 netcom10.telnet > zeego.1036: . 3995:4183(188) ack 80 win 16000
19:39:45.709778 zeego.1036 > netcom10.telnet: . ack 2535 win 31744
19:39:45.829778 netcom10.telnet > zeego.1036: . 4183:4589(406) ack 80 win 16000
19:39:45.829778 zeego.1036 > netcom10.telnet: . ack 2535 win 31744
19:39:46.059778 zeego.1036 > netcom10.telnet: . ack 2535 win 31744

****************************************************************************
Hang occurs around here (Maybe a bit earlier from the looks of the acks)
****************************************************************************

19:39:55.449778 netcom10.telnet > zeego.1036: . 3975:3995(20) ack 80 win 16000
19:39:55.449778 zeego.1036 > netcom10.telnet: . ack 2535 win 31744
19:39:55.509778 netcom10.telnet > zeego.1036: . 3995:4183(188) ack 80 win 16000
19:39:55.509778 zeego.1036 > netcom10.telnet: . ack 2535 win 31744
19:39:55.629778 netcom10.telnet > zeego.1036: . 4183:4589(406) ack 80 win 16000
19:39:55.629778 zeego.1036 > netcom10.telnet: . ack 2535 win 31744
19:39:55.859778 zeego.1036 > netcom10.telnet: . ack 2535 win 31744
19:40:05.479778 netcom10.telnet > zeego.1036: . 3975:3995(20) ack 80 win 16000
19:40:05.479778 zeego.1036 > netcom10.telnet: . ack 2535 win 31744
19:40:05.539778 netcom10.telnet > zeego.1036: . 3995:4183(188) ack 80 win 16000
19:40:05.539778 zeego.1036 > netcom10.telnet: . ack 2535 win 31744
19:40:05.659778 netcom10.telnet > zeego.1036: . 4183:4589(406) ack 80 win 16000
19:40:05.659778 zeego.1036 > netcom10.telnet: . ack 2535 win 31744
19:40:05.889778 zeego.1036 > netcom10.telnet: . ack 2535 win 31744
19:40:15.489778 netcom10.telnet > zeego.1036: . 3975:3995(20) ack 80 win 16000
<Cut>

Gordon Chaffee
chaffee@bugs-bunny.cs.berkeley.edu




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