On 09/14/2012 05:09 PM, M. Fioretti wrote: > Greetings, > > I have accounts on two Centos servers, A and B, each hosted on a remote > VPS by a different provider/datacenter. > > Until yesterday night, I could connect without problems via SSH to both > servers from my home Fedora 16 desktop. > > Yesterday I completed (fingers crossed) the switch to a different ADSL > provider. From the moment I turned on the modem on the new ADSL line, I > became unable to ssh into server A. All attempts abort with this message: > > ssh_exchange_identification: Connection closed by remote host > > I know that server A is still up and running, because the websites and > email services it runs are still up. Server B is still reachable via ssh, > no problem. The only difference between the two servers is that A runs > Centos 4.something, while B runs Centos 6.1 > > I have already done some online search on this problem, but all the pages > I have found discuss how to diagnose and fix it working on the server (*), > which is exactly what I can't do right now... > > Any clues on what may have happened, and if it could be related in any way > to differences (whatever they may be) between ADSL providers, instead of a > bizarre coincidence? > > Of course, I can and will ask the VPS provider to reboot the machine, but > I would also like to know your opinion on what exactly may have happened, > and how to prevent it in the future (also to pass your suggestions to the > provider). Check the /var/log/secure log. It could be that some bot is trying to brute force your server and the daemon is hitting the session limit. Regards, Dennis