Help with reading strace

Dan Track dan.track at gmail.com
Wed Mar 22 11:02:27 UTC 2006


On 3/22/06, Andy Green <andy at warmcat.com> wrote:
> Dan Track wrote:
>
> > sin_addr=inet_addr("10.11.10.1")}, 28) = 0
> > fcntl64(4, F_GETFL)                     = 0x2 (flags O_RDWR)
> > fcntl64(4, F_SETFL, O_RDWR|O_NONBLOCK)  = 0
> > gettimeofday({1143022459, 869414}, NULL) = 0
> > poll([{fd=4, events=POLLOUT, revents=POLLOUT}], 1, 0) = 1
> > send(4, "\367\201\1\0\0\1\0\0\0\0\0\0\7neptune\2l3\next"..., 43, 0) = 43
> > poll(
> >
> >
> >
> >
> >
> > [{fd=4, events=POLLIN}], 1, 5000)  = 0
>
> AIUI this is just telling you that poll blocked.  Use
>
> tcpdump
>
> to see what actually happens on the wire to provoke the blocking action,
> eg, ARP requests that are never satisfied?
>

Hi

Thanks for the reply.

Here's the associated tcpdump:

Any idea what is going on? I've tried to figure it out, but I'm not
that great an expert. Again the problem occurred at the space below in
the tcpdump.

6 578156318> (DF)
10:14:19.864519 neptune.example.com.1522 > 10.10.8.24.34881: . ack 89
win 5792 <nop,nop,timestamp 578156318 51374406> (DF)
10:14:19.867104 10.10.8.24.34882 > neptune.example.com.1522: S
949614679:949614679(0) win 5840 <mss 1460,sackOK,timestamp 51374406
0,nop,wscale 0> (DF)
10:14:19.867219 neptune.example.com.1522 > 10.10.8.24.34882: S
3261383070:3261383070(0) ack 949614680 win 5792 <mss
1460,sackOK,timestamp 578156319 51374406,nop,wscale 0> (DF)
10:14:19.867229 10.10.8.24.34882 > neptune.example.com.1522: . ack 1
win 5840 <nop,nop,timestamp 51374406 578156319> (DF)
10:14:19.867754 10.10.8.24.34882 > neptune.example.com.1522: P
1:88(87) ack 1 win 5840 <nop,nop,timestamp 51374407 578156319> (DF)
10:14:19.867881 neptune.example.com.1522 > 10.10.8.24.34882: . ack 88
win 5792 <nop,nop,timestamp 578156319 51374407> (DF)
10:14:19.868005 neptune.example.com.1522 > 10.10.8.24.34882: P
1:75(74) ack 88 win 5792 <nop,nop,timestamp 578156319 51374407> (DF)
10:14:19.868010 neptune.example.com.1522 > 10.10.8.24.34882: F
75:75(0) ack 88 win 5792 <nop,nop,timestamp 578156319 51374407> (DF)
10:14:19.868017 10.10.8.24.34882 > neptune.example.com.1522: . ack 75
win 5840 <nop,nop,timestamp 51374407 578156319> (DF)
10:14:19.868129 10.10.8.24.34882 > neptune.example.com.1522: F
88:88(0) ack 76 win 5840 <nop,nop,timestamp 51374407 578156319> (DF)
10:14:19.868242 neptune.example.com.1522 > 10.10.8.24.34882: . ack 89
win 5792 <nop,nop,timestamp 578156319 51374407> (DF)








10:14:24.878900 10.10.8.24.34883 > neptune.example.com.1522: S
955972141:955972141(0) win 5840 <mss 1460,sackOK,timestamp 51374908
0,nop,wscale 0> (DF)
10:14:24.879028 neptune.example.com.1522 > 10.10.8.24.34883: S
3271244119:3271244119(0) ack 955972142 win 5792 <mss
1460,sackOK,timestamp 578156820 51374908,nop,wscale 0> (DF)
10:14:24.879038 10.10.8.24.34883 > neptune.example.com.1522: . ack 1
win 5840 <nop,nop,timestamp 51374908 578156820> (DF)
10:14:24.879576 10.10.8.24.34883 > neptune.example.com.1522: P
1:88(87) ack 1 win 5840 <nop,nop,timestamp 51374908 578156820> (DF)
10:14:24.879706 neptune.example.com.1522 > 10.10.8.24.34883: . ack 88
win 5792 <nop,nop,timestamp 578156820 51374908> (DF)
10:14:24.879815 neptune.example.com.1522 > 10.10.8.24.34883: P
1:75(74) ack 88 win 5792 <nop,nop,timestamp 578156820 51374908> (DF)
10:14:24.879820 neptune.example.com.1522 > 10.10.8.24.34883: F
75:75(0) ack 88 win 5792 <nop,nop,timestamp 578156820 51374908> (DF)
10:14:24.879827 10.10.8.24.34883 > neptune.example.com.1522: . ack 75
win 5840 <nop,nop,timestamp 51374908 578156820> (DF)
10:14:24.879923 10.10.8.24.34883 > neptune.example.com.1522: F
88:88(0) ack 76 win 5840 <nop,nop,timestamp 51374908 578156820> (DF)
10:14:24.880042 neptune.example.com.1522 > 10.10.8.24.34883: . ack 89
win 5792 <nop,nop,timestamp 578156820 51374908> (DF)
10:14:24.882450 10.10.8.24.34884 > neptune.example.com.1522: S
944919838:944919838(0) win 5840 <mss 1460,sackOK,timestamp 51374908
0,nop,wscale 0> (DF)





Many thanks for your help.

Dan




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