web server blocking certain IP addersses

killian

For some reason people from certain and as far as i can see unrelated sites cannot access my work site - they get a page not found when the site is up and running and when others can view the site perfiectly. Has anyone come accross anything like this. It seems as though certain IP addresses are not being resolved by our server.
Could it be something to do with the DNS lookup?

mneylon

If it's a realtively new domain or the DNS has been changed it's possible that the site might be invisible temporarily

The other possibility is that they're IPs have been blocked by the server for some reason - though that's not very likely.

killian

thanks, the site has been up for over 14 months so it must be that the IP addresses are being blocked somehow, although I can't imagine why

mneylon

If the server is running PortSentry or similar it will refuse connections on all ports from its blacklist of IPs.
Is it a virtually hosted site or dedicated server?

killian

It is on a dedicated server - Apache

nahdoic

A page not found error wouldn't necessarily indicate their requests are being blocked.

Are these people able to view your site when they type in the IP address of your site, rather than the domain name?

killian

For both the IP address and domain name, it says website found, (in the below title bar), and then doesn’t load….

mneylon

Originally posted by killian
For both the IP address and domain name, it says website found, (in the below title bar), and then doesn’t load….

So it's giving a blank screen with no other messages?

killian

The page cannot be displayed
The page you are looking for is currently unavailable. The Web site might be experiencing technical difficulties, or you may need to adjust your browser settings.

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Please try the following:

Click the Refresh button, or try again later.
If you typed the page address in the Address bar, make sure that it is spelled correctly.
To check your connection settings, click the Tools menu, and then click Internet Options. On the Connections tab, click Settings. The settings should match those provided by your local area network (LAN) administrator or Internet service provider (ISP).
If your Network Administrator has enabled it, Microsoft Windows can examine your network and automatically discover network connection settings.
If you would like Windows to try and discover them,
click Detect Network Settings
Some sites require 128-bit connection security. Click the Help menu and then click About Internet Explorer to determine what strength security you have installed.
If you are trying to reach a secure site, make sure your Security settings can support it. Click the Tools menu, and then click Internet Options. On the Advanced tab, scroll to the Security section and check settings for SSL 2.0, SSL 3.0, TLS 1.0, PCT 1.0.
Click the Back button to try another link

mneylon

Is there any server-side scripting in the page? Eg. PHP

killian

Yes there is PHP and .tcl (like Perl but with more logic built in I think)

mneylon

I had a similar problem after upgrading PHP, but that can't be your case if other people can see the page. Could you post the URL? It might make it a little easier. (If you don't want to post it here send me a PM)