Re: [squid-users] TCP_MISS/504 when accesing www.citibank.com

Thanks Amos,

A dig to www.citibank.com gives two different ips, changing one for
the other after a short period of time, one of them works fine and
squid 2.7 is able to get the page and the other one fails.

Using tcpdump I have taken captures for both, while using debian
package for squid 2.7.stable9, these are the results:

In both of them squid sends a "GET HTTP/1.0":

     1) The one that works replays with a "HTTP/1.1 301 Moved
Permanently", that TCP session is close and another one is open squid
now asking for the new URL, finally being able to retrieve it and
serve it fine.

     2) The other one doesnt reply at all to the inital "GET HTTP/1.0"
petition and therefore there are a few TCP retransmissions of it until
it receives a FIN,ACK packet from the server.

I tried the same but using squid 3.1.6 instead, again in both servers,
and it works in both!. The difference being that squid 3.1 instead of
sending a"GET HTTP/1.0" sends a "GET HTTP/1.1", getting the "HTTP/1.1
301" response in both cases. So, to the light of these results, is
seems that the second server (the one that fails) does not
understand/talk HTTP/1.0, dont you think? is this possible?.

Thank you,
Fred.

"UNIX is very simple, it just needs a genius to understand its simplicity."
-- Dennis Ritchie, D.E.P.

On Wed, Nov 9, 2011 at 5:37 AM, Amos Jeffries <squid3_at_treenet.co.nz> wrote:
> On 9/11/2011 12:29 a.m., feralert wrote:
>>
>> Hi all,
>>
>> I'm new on the list so hi everyone and please do excuse my english.
>>
>> And now down to bussiness :)
>>
>> Im having trouble accessing www.citibank.com with squid 2.7. I'm
>> actually trying from two different platforms (Debian Lenny linux box
>> running 2.7.STABLE3 and NetBSD running  2.7.STABLE7), using different
>> connections to the internet and both getting weird results.
>>
>>
>> * ) With the NetBSD machine:
>>
>> What i usually get in the browser is a " (110) Connection timed out",
>> and a "TCP_MISS/504" in the servers logs.
>>
>>> While trying to retrieve the URL: http://www.citibank.com/
>>> The following error was encountered:
>>> Connection to 192.193.219.58 Failed
>>> The system returned:
>>>    (110) Connection timed out
>>> The remote host or network may be down. Please try the request again.
>>
>> 03:16:39 120355 10.5.5.236 TCP_MISS/504 1454 GET
>> http://www.citibank.com/ - DIRECT/192.193.219.58 text/html
>>
>>
>> But sometimes (ina very few rare occasions) it gets through and I see
>> the following:
>>
>> 1320746405.173  15615 10.5.5.236 TCP_MISS/200 6985 CONNECT
>> metrics1.citibank.com:443 - DIRECT/63.140.40.2 -
>>
>> And in the browser I see that I get redirected to
>> "https://online.citibank.com/US/Welcome.c". From there on I have no
>> trouble surfing the website. Also, if I try go directly to
>> "https://online.citibank.com" works every time.
>>
>>
>>
>> * ) With the linux one:
>>
>> With this one I never gotten through (maybe I havent tried as many
>> times), I also get the "Connection timed out"  and "TCP_MISS/504", and
>> also a"Zero Sized Reply" and a "TCP_MISS/502":
>>
>> The browser shows:
>>
>>> While trying to retrieve the URL: http://www.citibank.com/
>>> The following error was encountered:
>>> Zero Sized Reply
>>> Squid did not receive any data for this request.
>>
>> And in the logs I get:
>> 03:01:03 150396 10.5.5.236 TCP_MISS/502 1334 GET
>> http://www.citibank.com/ - DIRECT/192.193.103.222 text/html
>> 03:03:35 151215 10.5.5.236 TCP_MISS/504 1477 GET
>> http://www.citibank.com/favicon.ico - DIRECT/192.193.103.222 text/html
>>
>>
>
> These seems to be all symptoms of either TCP connection setup problems or
> ICMP blocking. The "Zero Sized Reply" hints that it is more likely MTU
> problems and ICMP blocking somewhere. Where Squid can locate and send data
> to the server, but nothing comes back (ie the packet sent was too big, but
> the ICMP reply telling the Squid machine to send smaller packts never got
> delivered).
>
> Amos
>
Received on Wed Nov 09 2011 - 20:54:16 MST