Re: [squid-users] 502 Bad gateway

On Sat, 2012-10-13 at 18:05 +1300, Amos Jeffries wrote:
> On 13/10/2012 2:18 a.m., Leonardo wrote:
> > Hi,
> >
> > I'm getting "502 bad gateway" while attempting to access the site
> > ibs.it. This happens with squid 3.2.2 and 3.2.0.19 at least. It does not
> > happen with squid 2.7.x series (not tested with all minor revisions
> > though).
> >
> > Anyone else getting the same error?
>
> Beyond the generic HTTP status code what else do you have? Squid logs
> and the content of that 503 response would be helpful.

1350283892.429 129 10.44.65.254 TCP_MISS_ABORTED/200 2901 GET
http://www.ibs.it/ - HIER_DIRECT/www.ibs.it text/html

> > I've dumped the traffic with squid and without squid (it works without
> > proxy), and as far I could tell, there's no reverse proxy doing bad
> > stuff.
>
> It's not about a reverse proxy. It's about something somewhere in the
> relay chain not being available. The error page itself will tell more.

"502 Bad Gateway
The server returned an invalid or incomplete response."

> > The answer from the site appears to be same in both cases. With
> > squid, I see that after the second response packet, after the GET
> > request, my proxy closes the connection with FIN,ACK, and all subsequent
> > response packets get an RST.
>
> Sounds perfectly normal behaviour for TCP shutting down a connection.
>
> But are you saing the proxy sends FIN or FIN+ACK ? which one determines
> which end is doing the closure.

Sorry, I was not clear in that. The proxy sends one packet with FIN,ACK
flags, effectively shutting down the connection.

> > What could it be the issue?
>
> One of the services needed by Squid to provide a response is not
> working. Upstream HTTP server, DNS server, ICAP server, helper problem,
> TCP errors, URL scheme unknown, .... could be any one of those or
> something else entirely.

I guess I need to turn on some debugging in order to find out what's
wrong. I'm trying to figure out the right Section Number to turn on.

Thanks!

- leonardo