NOTE - If you are trying to remotely log into a desktop machine directly (for example, Praesepe) you will (and should!) be denied access. The Astronomy Cluster is set up in such a way that access to the individual machines are only allowed from astronomy. I.e., you must first remotely (SSH) into astronomy, and then you'll be able to go to the individual machine.
If there are multiple, frequent, failed login attempt - astronomy will flag the IP of the address and deny SSH access from the offending IP. This is done for security reasons. However, occasionally users will get trapped in this security measure should they have multiple failed login attempts.
Usually you'll get an error like:
"kex_exchange_identification: read: Connection reset by peer"
If this happens, it can only be fixed by the system admins (Jon and Zach). If you are getting SSH issues, please notify issues at astronomy.nmsu.edu and we'll clean up your IP from astronomy's block list!
If you get the following error:
@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@ @ WARNING: REMOTE HOST IDENTIFICATION HAS CHANGED! @ @@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@ IT IS POSSIBLE THAT SOMEONE IS DOING SOMETHING NASTY! Someone could be eavesdropping on you right now (man-in-the-middle attack)! It is also possible that a host key has just been changed. The fingerprint for the RSA key sent by the remote host is <Long string of characters> Please contact your system administrator. Add correct host key in /home/path/user/.ssh/known_hosts to get rid of this message. Offending RSA key in /home/path/user/.ssh/known_hosts:4 RSA host key for machine has changed and you have requested strict checking. Host key verification failed.
That means the identification has changed in the system. Usually, this is caused when machines are updated to a newer version of CentOS (and Zach forgets to fix it before you log in!). Please notify us ASAP if you see this message! Even though 99% of the time its harmless, its good to track. If you get this message, as it says in the warning, this can be solved by editing your known_hosts file in ~/.ssh/ and removing the offending RSA Key (just delete the line). If you are not comfortable with editing your ~/.ssh/known_hosts file, please feel free to ask us via issues at astronomy.nmsu.edu to fix it for you.