I installed latest version of PopTop on a Slackware machine. I got it up and running, I can connect and get authenticated and I can get to other hosts on the Internet but I have a weird problem. PopTop only allows me to connect to other machines using SSH. So, for example my desktop is A, PopTop server is B and third machine is C. Machine C is running Terminal Server, SSH server and VNC server. So if A tries to connect to C using SSH everything works fine. But if A tries to connect to C using RDP or VNC protocol then the connections time out and there is nothing in the PopTop log file indicating why. Connections to machine C using RDP and VNC work fine if not tunneled though machine B (PopTop). Is there some reason why the PopTop server (B) allows SSH traffic to pass through and blocks all other traffic? Do I have to explicitly tell PopTop what to allow and what to block? That would suck, but if that is the solution, please let me know how can I do that.
Thanks a lot.
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None of the 3 suggested issues is the case. Machine C allows RDP connections when they are directly established (i.e. from A to C without going through the VPN host B). The only thing that comes to my mind is that the VPN host B block all ICMP (ping) traffic with a firewall rule. The reason is that it is facing the Internet without any firewall and blocking pings makes it more difficult to detect. Could that be the reason? Does RDP need ping to operate?
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1 Perhaps machine C is blocking the traffic. Have to attempted the connection from server B to test that theory?
2 Perhaps there is an existing firewall rule in place that is dropping the packets. Try the iptables -n -L -v command to list all the netfilter rules on Server B that could be dropping packets. If that doesn't help, try connecting from desktop A to a different Linux server (D) on server B's subnet. When attempting to connect, do a tcpdump on server D to confirm that the packates are making it that far.
3 Poptop doesn't restrict traffic by default, but you could check /etc/ppp/ip-up to see if a firewall script is being loaded.
Good luck!
-Bob
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Hi,
I installed latest version of PopTop on a Slackware machine. I got it up and running, I can connect and get authenticated and I can get to other hosts on the Internet but I have a weird problem. PopTop only allows me to connect to other machines using SSH. So, for example my desktop is A, PopTop server is B and third machine is C. Machine C is running Terminal Server, SSH server and VNC server. So if A tries to connect to C using SSH everything works fine. But if A tries to connect to C using RDP or VNC protocol then the connections time out and there is nothing in the PopTop log file indicating why. Connections to machine C using RDP and VNC work fine if not tunneled though machine B (PopTop). Is there some reason why the PopTop server (B) allows SSH traffic to pass through and blocks all other traffic? Do I have to explicitly tell PopTop what to allow and what to block? That would suck, but if that is the solution, please let me know how can I do that.
Thanks a lot.
None of the 3 suggested issues is the case. Machine C allows RDP connections when they are directly established (i.e. from A to C without going through the VPN host B). The only thing that comes to my mind is that the VPN host B block all ICMP (ping) traffic with a firewall rule. The reason is that it is facing the Internet without any firewall and blocking pings makes it more difficult to detect. Could that be the reason? Does RDP need ping to operate?
There are a few possibilities.
1 Perhaps machine C is blocking the traffic. Have to attempted the connection from server B to test that theory?
2 Perhaps there is an existing firewall rule in place that is dropping the packets. Try the iptables -n -L -v command to list all the netfilter rules on Server B that could be dropping packets. If that doesn't help, try connecting from desktop A to a different Linux server (D) on server B's subnet. When attempting to connect, do a tcpdump on server D to confirm that the packates are making it that far.
3 Poptop doesn't restrict traffic by default, but you could check /etc/ppp/ip-up to see if a firewall script is being loaded.
Good luck!
-Bob