Cannot reach Debian firewall from certain internet locations

pda23 · 10-11-2009, 09:33 AM

Dear All,

There is a Debian firewall, which works fine, but there is one strange problem: There are some places on the internet, from where it is not possible to access the server (VPN, web, ping, etc. doesn't work). It works almost from everywhere, just a couple of places experience this problem. Do you have any idea? Have you experienced anything like this? Traceroute says that the packets are lost at the server.

Thank you for your suggestions.

carltm · 10-11-2009, 10:40 AM

Are you using ping to determine accessibility? If so, ping is not a
reliable indicator. Ping is often restricted either temporarily or
permanently across portions of the Internet.

pda23 · 10-11-2009, 03:01 PM

Quote:

Originally Posted by carltm

Are you using ping to determine accessibility? If so, ping is not a
reliable indicator. Ping is often restricted either temporarily or
permanently across portions of the Internet.

Dear carltm!

Thank you for your reply. I use ping and traceroute during the troubleshooting. For example I ping/traceroute it from location A , it doesn't work, but in the same time it works from location B. What do you recommend to use instead of ping?

carltm · 10-13-2009, 06:25 PM

Use whatever services you have running on the server. If you have
a webserver, test port 80. For ssh test port 22.

There is a handy utility named nmap that can test tcp ports. For
example, to test ssh, on serverA you'd run "nmap -p 22 serverB".