[erlang-questions] crash dump at ejabberd startup

Michael Santos <>
Wed Nov 17 15:48:54 CET 2010


On Wed, Nov 17, 2010 at 04:59:52AM +0100,  wrote:

> > It might help. I think the quickest way to debug this would be to:
> 
> donesults below ...

Did you run these steps concurrently or sequentially? e.g., when you
brought up the erlang node, was the debug epmd running?

epmd (with debug switches) needs to be running in one shell, the tcpdump's
(with the "-n" switch) in another. Then start up the Erlang node.

> # tcpdump -i lo0 -vv port 4369
> tcpdump: WARNING: lo0: no IPv4 address assigned
> tcpdump: listening on lo0, link-type NULL (BSD loopback), capture size 96 
> bytes

Was the output below from the dump of the loopback?

> and tcpdump output:
> 
> 03:33:15.964680 IP (tos 0x0, ttl 64, id 24389, offset 0, flags [DF], proto 
> TCP (6), length 60, bad cksum 0 (->4f37)!)
>     mail.kepos.org.10975 > mail.kepos.org.4369: Flags [S], cksum 0xd692 
> (correct), seq 3123827793, win 65535, options [mss 16344,nop,wscale 
> 3,sackOK,TS val 77847542 ecr 0], length 0
> 03:33:15.964701 IP (tos 0x0, ttl 64, id 24390, offset 0, flags [DF], proto 
> TCP (6), length 60, bad cksum 0 (->4f36)!)
>     mail.kepos.org.4369 > mail.kepos.org.10975: Flags [S.], cksum 0x776a 
> (correct), seq 3252621940, ack 3123827794, win 65535, options [mss 
> 16344,nop,wscale 3,sackOK,TS val 2304704868 ecr 77847542], length 0
> 03:33:15.964712 IP (tos 0x0, ttl 64, id 24391, offset 0, flags [DF], proto 
> TCP (6), length 52, bad cksum 0 (->4f3d)!)

>     mail.kepos.org.4369 > mail.kepos.org.10975: Flags [F.], cksum 0xbd43 
> (correct), seq 1, ack 19, win 8960, options [nop,nop,TS val 2304704868 ecr 
> 77847542], length 0
> 03:33:15.964906 IP (tos 0x0, ttl 64, id 24394, offset 0, flags [DF], proto 
> TCP (6), length 52, bad cksum 0 (->4f3a)!)
>     mail.kepos.org.10975 > mail.kepos.org.4369: Flags [.], cksum 0xbd43 
> (correct), seq 19, ack 2, win 8960, options [nop,nop,TS val 77847542 ecr 
> 2304704868], length 0
> 03:33:15.964929 IP (tos 0x0, ttl 64, id 24395, offset 0, flags [DF], proto 
> TCP (6), length 52, bad cksum 0 (->4f39)!)
>     mail.kepos.org.10975 > mail.kepos.org.4369: Flags [F.], cksum 0xbd42 
> (correct), seq 19, ack 2, win 8960, options [nop,nop,TS val 77847542 ecr 
> 2304704868], length 0
> 03:33:15.964937 IP (tos 0x0, ttl 64, id 24396, offset 0, flags [DF], proto 
> TCP (6), length 52, bad cksum 0 (->4f38)!)
>     mail.kepos.org.4369 > mail.kepos.org.10975: Flags [.], cksum 0xbd43 
> (correct), seq 2, ack 20, win 8959, options [nop,nop,TS val 2304704868 ecr 
> 77847542], length 0
> ^C

Do not resolve IP addresses. We need to see the source and destination
IP addresses.

So something on port 4369 (on whatever "mail.kepos.org" is) is accepting
and closing the connection. If it is not epmd (because there is nothing
in your debug log), what is it?

> Juust to exde any misconfiguation on the machine I allso  tried itt again 
> switching off the firewall for this test: same result.

Always a good idea.



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