[erlang-questions] rabbit, epmd and bonded interfaces woes

Michael Santos <>
Fri Jan 13 23:05:20 CET 2012


On Fri, Jan 13, 2012 at 03:25:21PM -0500, Leonard Boyce wrote:
> On Friday, January 13, 2012 03:15:16 PM Michael Santos wrote:
> > On Fri, Jan 13, 2012 at 02:52:06PM -0500, Leonard Boyce wrote:
> > > <snip>
> > That patch reverts to the old behaviour of epmd (allow all query types
> > from remote clients).
> > > <snip>
> > Newer versions of epmd consider connections with the same source and
> > destination address as local. What are the source and destination
> > addresses for the TCP connection to epmd?
> 
> looking at tcpdump the command "erl -sname somestrangename" calls epmd from 
> the public IP of the machine. "web1" is the aliased to 127.0.0.1 in 
> /etc/hosts. With the alias removed the tcpdump shows 'localhost' in place of 
> 'web1'.

Try tcpdump -n, the name lookups are suppressed.

> 14:41:27.874188 IP (tos 0x0, ttl 64, id 61958, offset 0, flags [DF], proto TCP 
> (6), length 52)
>     XX.XX.XX.XX.42982 > web1.4369: Flags [F.], cksum 0x5877 (correct), seq 30, 
> ack 2, win 257, options [nop,nop,TS val 24962735 ecr 24962735], length 0
> 
> As far as I understand the above command 'should' be binding and calling epmd 
> from 'localhost', not an arbitrary mounted IP.

Yup, Erlang nodes are hard coded to go to 127.0.0.1. You should see the
source as 127.0.0.1.

The server is in a weird state. Anything wrong with the loopback or the
routes?

I remember someone had a similar issue that cleared up after a reboot.
Might want to try that, if you haven't already.



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