= I'm getting a scary message when I try to login to my account using secure shell or secure FTP = When you try to [wiki:secure_shell secure shell] (ssh) or [wiki:sftp secure FTP] to our servers, you may get a message that looks like this: {{{ @@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@ @ 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 the RSA host key has just been changed. }}} It's probably a message you haven't seen before and it may be confusing and even disturbing. It's showing because we have changed the "host keys" for most of our servers due to a [wiki:openssl_vulnerability_2008-05 security problem] discovered in the program used to generate the keys. The two affected servers most commonly used by members are: mandela.mayfirst.org and malcolm.mayfirst.org. Their new fingerprints are: {{{ mandela.mayfirst.org: b5:c9:45:1e:b9:54:66:d7:a6:5d:3b:70:dc:0a:e4:14 malcolm.mayfirst.org: 75:a7:ab:16:36:61:43:f2:b6:08:4d:87:fe:2e:6a:5b }}} To get the correct, current "fingerprint" of other servers, please see our [wiki:fingerprints fingerprints] page. You'll need the fingerprint to follow the instructions below and make the message disappear. == Making the error message go away == === Using linux === You will need to edit your ~/.ssh/known_hosts file. The error message should specify the line number of the "offending" key. Simply delete that line in the file and try again. For example, if you were trying to connect to `chavez.mayfirst.org`, you can remove the offending key via the command line with: {{{ ssh-keygen -R chavez.mayfirst.org }}} === Using Windows === You should see the new fingerprint. [wiki:fingerprints Confirm that it is correct] and then select the option to save this key permanently. === Using Macintosh === Similarly to Linux, you will need to edit your ~/.ssh/known_hosts file. The error message will specify the line number of the "offending" key; for example, {{{ Offending key in /Users/Jack/.ssh/known_hosts:26 }}} Here, 26 is the line number of the "offending" key. Edit ~/.ssh/known_hosts and delete the line. To do this using the vim text editor, type the following at the prompt in Terminal: {{{ vi ~/.ssh/known_hosts }}} When the file opens, type {{{ :26 }}} replacing "26" with your offending line number to jump to that line in the file. The name or IP address of the server you were trying to connect to should appear at the beginning of this line. Type {{{ dd }}} to delete the line, then type {{{ :wq }}} to save your changes and quit. Then, try to connect to the server again. You'll likely get a message saying that the authenticity of the host cannot be established; type "yes" to continue connecting and the new host key will be saved into your known_hosts file. == What are host keys? == Host keys are random bits of text that are unique to every server. The randomness of the keys allows us to have a secure, encrypted connection between you and the server.