Can access website, but can't ping it, nor access via FTP

Question

I'm having a problem connecting to a server by other way than HTTP.
Connecting via FTP ends with timeout, as well as pinging:

C:\Users\folmert>ping wroclaw-elektryk.pl

Pinging wroclaw-elektryk.pl [87.98.239.4] with 32 bytes of data:

Request timed out.

I can ping other websites, so I don't think the problem lies on my side. I believe it's rather because of some some strange server configuration, am I right? I want to make sure before writing to hosting provider.

Solution 1

Comparing the output of traceroute -n wroclaw-elektryk.pl and traceroute -n -T -p 80 wroclaw-elektryk.pl I find that the route is varying a lot, which can make debugging a bit tricky. But I also found that five hops before reaching the server, I hit a misconfigured firewall, which is responsible for ping not working.

Based on whois data for the involved hops, it appears the misconfigured firewall is on the link from the backbone provider to the hosting provider. I think a hosting provider should not be enforcing this kind of filters on their customers, so if you cannot get them to disable it, you may be better off switching hosting provider.

Using traceroute -n -T -p 21 wroclaw-elektryk.pl and telnet wroclaw-elektryk.pl 21, I find that the connection to the server works just fine. But the FTP server doesn't send any response code after the TCP connection has been established.

Reasons I have previously seen for a server not sending any response code on a newly established TCP connection include:

• Defective storage media
• Kernel bug
• Severely overloaded server
• Server configured to perform reverse DNS before sending a response, and somehow failing.

Solution 2

This is happening mostly because they have block access for icmp protocol and ftp ports. If you need to do because it's a customer facing problem, ask them to open up (allow access on the firewall configuration) the icmp and ftp ports.

Regards,

ankso

Solution 3

I suppose this is an firewall issue, only HTTP access is allowed to your remote host. You can check this using nmap. Try using man nmap first if you need more details about the command.

Comments

[erimar77]

What are you trying to accomplish? Denying ICMP requests is normal-ish, are you expecting FTP to be available?

[van_folmert]

how exactly do I check it? I've discovered 1000 open ports which doesn't tell me much, here's the output: pastebin.com/ypyc5Zba

[ibedelovski]

There you can check if your FTP port is allowed for outside access. For example if FTP is on the output list, you should be able to access the FTP server. If you are not able to access the FTP server again there might be other issues...