Connection problems

Troubleshooting your connection

If the cluster interactive nodes have recently been re-installed (you will have received an email about this), you may get a message as follows:

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@ WARNING: POSSIBLE DNS SPOOFING DETECTED! @

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The RSA host key for hepcms.umd.edu has changed,

and the key for the corresponding IP address 128.8.164.21

is unchanged. This could either mean that

DNS SPOOFING is happening or the IP address for the host

and its host key have changed at the same time.

Offending key for IP in /Users/username/.ssh/known_hosts:229

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@ WARNING: REMOTE HOST IDENTIFICATION HAS CHANGED! @

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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

82:b3:db:a7:4d:34:77:5a:50:49:38:56:4e:3b:8e:59.

Please contact your system administrator.

Add correct host key in /Users/username/.ssh/known_hosts to get rid of this message.

Offending RSA key in /Users/username/.ssh/known_hosts:108

RSA host key for hepcms.umd.edu has changed and you have requested strict checking.

Host key verification failed.

- When we re-install the system the hepcms RSA key does change. You can either delete your ~/.ssh/known_hosts file or remove all lines with hepcms. In your next login, you will be asked to accept the new key with a "yes".
- To avoid this ssh key issue, make a file .ssh/config (on your local machine) with following lines:
- Host hepcms*.umd.edu
- StrictHostKeyChecking no
- UserKnownHostsFile /dev/null

ssh -Y username@hepcms.umd.edu

ssh_exchange_identification: Connection closed by remote host

- If you try to connect and get the message above it means you have had too many password failures from your IP address and you have been blocked. You need to find your IP address (whatismyip.com), and Contact the sysadmins to remedy the problem.