Since few days, my dedicated server (Ubuntu 13.04) is no longer able to ping or connect to my NAS through DNS (hostname -> kr1.synology.me ) . The IP address ( 126.96.36.199 ) address against , is still reachable, I can ping to it, and also connect it via SSH.
Concretely I can do this :
sudo ssh firstname.lastname@example.org sudo ping 188.8.131.52
But not this ( whereas before yes) :
sudo ssh email@example.com sudo ping example.com
The problem is not from NAS side, because I can still reach it with firstname.lastname@example.org from my local machine. The problem occurs only from my dedicated server.
Here are some options I did recently on my server:
- I installed ufw and configured it to only allow some ports
- I prevented the ability to connect as root in SSH
- I prevented the ability to connect with SSH password (key required)
- I installed and configured denyhosts and fail2ban
- I installed rkhunter and chkrootkit
- I added no recursion & "Not Disclosed" to Bind9 configuration
- I added nospoof to
Will you help me solve the problem? I spent several hours on it and can not clearly identify the cause.