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Home > Archive > Apache Server configuration support > October 2006 > Web server unavailable from some external locations
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Web server unavailable from some external locations
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| Mahoney 2006-10-19, 3:27 am |
| Running
Apache/2.0.59 (Win32) DAV/2 mod_auth_sspi/1.0.4 mod_ssl/2.0.59 OpenSSL/0.9.8c SVN/1.4.0 Server
on Windows Server 2003.
I reckon about 60% of external people can see the website, and 40% cannot. Unfortunately all three of my external attempts to get through to it fail, from work, client site and my PDA's GPRS. IE and Firefox both sit waiting for a response forever if I request a legitimate file. If I request a nonsense one I get ana ccurate 404 from the server.
Apache does seem to log my attempts that fail as 200 requests. So my request is getting through; but no response gets back to me. nmap run from work also correctly identified my server as running Apache configured the way I have it, so nmap can get a response back. Just not, it would seem, any web browser.
Obviously it is not a firewall or DNS issue as lots of people can get to the site from outside using the domain name, I can get a 404 from the server, nmap can get a response and my requests get logged.
Any bright ideas? I'm currently very confused. It's either Apache (unlikely), my router or my ISP losing or misdirecting the HTTP response, I presume... unless certain networks refuse HTTP responses from my ISP? But my ISP swears blind that several companies run web servers using accounts with them. | |
| Mahoney 2006-10-19, 3:24 pm |
| Someone on the Apache users mailing list sorted it for me.
It was to do with MTU (basically the number of bits or bytes, not sure which, in a package). My ISP expects an MTU of 1458, and Windows defaults to an MTU of 1500. When your browser and my server negotiate to work out how to communicate, some corporate firewalls permit the communication that tells my server to drop the MTU down dynamically - and some don't, so if you were behind a firewall that doesn't that would explain why you couldn't see anything, and others could.
Set my routers and Windows to an MTU of 1458, and now it works. In Windows it requires a registry edit, easy to find via google:
http://www.winguides.com/registry/display.php/280
So ask your ISP what your MTU should be and set your routers and your server to that value, would be my advice, if you find this thread because you had a similar issue. |
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