Solved

Certain websites not opening - might be squid problem

Posted on 2010-11-17
7
1,641 Views
Last Modified: 2012-05-10
Hi

Since monday we have a problem at one of our three campuses where certina websites are extremely slow to open and others wont open at all (time - outs).

The only common denominator in these sites I can see is that they all require logins yet other sites like gmail(or any google login sites) , twitter, forums and expert exhange have no problem.

some of the sites that wont open:
www.facebook.com (marketing purposes ...really)
http://students.autodesk.com
http://autodesk.starttest.com


We are running a clarkconnect server (ClearOS - Centos) with a squid proxy non transparent.
All three campuses have the same setup and the other two are working fine.

Thank you

0
Comment
Question by:QuintusSmit
  • 4
  • 3
7 Comments
 
LVL 12

Expert Comment

by:Kent W
ID: 34161705
The login may just be a coincidence.  This sure sounds like an MTU based problem to me.
What MTU is this node using, and what is the actual connection type?
0
 
LVL 1

Author Comment

by:QuintusSmit
ID: 34161857
The connection is a dsl line (1024mb line). How do I check the MTU size?
0
 
LVL 12

Accepted Solution

by:
Kent W earned 250 total points
ID: 34162627
Ahhh...as is the most likely culprits. :)  Happens a lot on DSL.
Check your router, it will probably auto-negotiate MTU to something like 1490 (most Broadband / Lan use 1500).
The problem is, your client computers are using 1500 by default, so you will need to download a program like
DRTCP (free), and match the MTU on your router on the NIC, lan or wireless interface, of your client computers.
It's annoying, but quite common on DSL lines.  Just google DRTCP, it will be available at dslreports.com.
Run the exe, select the NIC(s) you need to change, select the MAXMTU window and change 1500 to match your router...if you can't find that value, try 1490.  Save, reboot, and wham, all the sudden pages start loading.
99.9% sure this will fix your problem.  If 1490 doesn't work, or work well, lower it by 10s down to a max of about 1460.  If your MTU doesn't become happy, it's something else.
But I bet my first wife's alimony this will fix you up.  
0
U.S. Department of Agriculture and Acronis Access

With the new era of mobile computing, smartphones and tablets, wireless communications and cloud services, the USDA sought to take advantage of a mobilized workforce and the blurring lines between personal and corporate computing resources.

 
LVL 1

Author Comment

by:QuintusSmit
ID: 34186067
@mugojava: so i was wondering..should i give you my bank details for those alimony payments or would you prefer to send cheques? :)

At the moment that solution is not working however, I would still like to test it more extensively on some other pc's - I have been very busy but will keep you updated.
0
 
LVL 12

Expert Comment

by:Kent W
ID: 34193077
Really?  That surprises me, when the old "DSL" +"some pages slow or not loading" issue comes up, especially if some sites are just fine, with no rhyme or reason, I have yet to NOT have it be an MTU issue. Make sure you have the actual adapter you are connecting to the net with (Ie, don't select the LAN nic if you connect to the router with a wireless adapter, and vice-verca) when setting the MTU value.
On a hilarious note, one of the sites that usually had problems with askewed MTU was "marthastewart.com" :O)  Now that's funny, I don't care who ya are!"
0
 
LVL 1

Author Comment

by:QuintusSmit
ID: 34226359
@mugojava

Thank you for your help and input. I'm going to award you the points for that. The problem it turns out was something with the squid proxy. Don't really have an answer but as soon as we narrowed it down to that we reinstalled squid and everything was fine.
0
 
LVL 12

Expert Comment

by:Kent W
ID: 34227853
Well, I do appreciate that, and if this helps, I've also had a similar problem with Squid on DSL...you probably looked already on this, but just in case, check out Path MTU Discovery (PMTUD) and things it can hose.  Other culprits... ECN and TCP Window Scaling can also cause Squid to hang during certain conditions.
Sure hope that helps some way. :)
0

Featured Post

Simplifying Server Workload Migrations

This use case outlines the migration challenges that organizations face and how the Acronis AnyData Engine supports physical-to-physical (P2P), physical-to-virtual (P2V), virtual to physical (V2P), and cross-virtual (V2V) migration scenarios to address these challenges.

Question has a verified solution.

If you are experiencing a similar issue, please ask a related question

Linux users are sometimes dumbfounded by the severe lack of documentation on a topic. Sometimes, the documentation is copious, but other times, you end up with some obscure "it varies depending on your distribution" over and over when searching for …
It’s 2016. Password authentication should be dead — or at least close to dying. But, unfortunately, it has not traversed Quagga stage yet. Using password authentication is like laundering hotel guest linens with a washboard — it’s Passé.
Connecting to an Amazon Linux EC2 Instance from Windows Using PuTTY.
This demo shows you how to set up the containerized NetScaler CPX with NetScaler Management and Analytics System in a non-routable Mesos/Marathon environment for use with Micro-Services applications.

790 members asked questions and received personalized solutions in the past 7 days.

Join the community of 500,000 technology professionals and ask your questions.

Join & Ask a Question