I am a new user of Putty and SSH, having never connected to a server this way before.

There are TWO remote servers I need to connect to.

I can get Putty to connect to Server A with no problem.

With Server B however, it times out. The strange thing is that my friend is able to connect to the same Server B without any problem.

So, the fact that I can connect to Server A suggests that my own PC is not blocking Putty from making connections, and the fact that my friend can connect to Server B suggests that it is set up correctly to accept connections on port 22.

What could be blocking my connection to Sever B?

Paul

I understand you are getting no response back from server B rather than a refusal? I am not that familiar with firewalls on MS machines, but your symptom would make the firewall a leading contender I would think. Can you successfully ping server B? Or traceroute?

If you have a *nix box available you might see if you can connect from it, and if not use a packet sniffer to see what is going on. Or maybe there are packet sniffers you can use on MS?

Thanks for replying.

We seem to have partially solved the problem by having APF disabled on the remote server.

According to our hosting company: "APF is a graphical dynamic proactive software that uses iptables, which is a Linux firewall software. It actively detects attacks on your server and tries to neutralize them."

I say "partially solved" because APF is still off, and we are told it should be on! So we now have to sort out how to have APF back on but not blocking my own IP address.

APF apparently stands for Advanced Protection Firewall assuming my link is what you have running. I would think it would be quite configurable to get around whatever problem you are having w/o turning it off completely -- assuming you can figure out what is causing the problem. I did notice that it can be configured to use a dshield block list. I wonder if you are on that list. That would be a distinct possibility if you have a dynamically assigned IP address (where a previous user of the IP address used it maliciously, or was compromised). I believe you can check to see if your IP address is on that list at dshield.org. You can also check it at isc.sans.org , where on arrival your address will be in their "IP Lookup" search box.

You will need to remove your IP from the following file.

/etc/apf/deny_hosts.rules

Then add your IP to this file.

/etc/apf/allow_hosts.rules

Then restart APF. That will ensure that your IP is safe from being blocked.

Thanks everyone for your help. Much appreciated. I'm sure we'll get this problem solved now.

The following kluge may offer a tmp solution:

PuTTY to A, then (inside PuTTY) ssh from A to B. This assumes that B is not blocking A.