Remove a line from a file using sed (useful for updating known SSH server keys when they change)
user@host:~$ ssh user@server @@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@ @ WARNING: POSSIBLE DNS SPOOFING DETECTED! @ @@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@ The RSA host key for server has changed, and the key for the corresponding IP address 1.2.3.4 is unknown. 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. @@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@ @ 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. The fingerprint for the RSA key sent by the remote host is ff:ff:f:ff:ff:ff:ff:ff:ff:f:ff:ff:ff:ff Please contact your system administrator. Add correct host key in /home/user/.ssh/known_hosts to get rid of this message. Offending key in /home/user/.ssh/known_hosts:49 RSA host key for server has changed and you have requested strict checking. Host key verification failed. user@host:~$ sed -i '49d' ~/.ssh/known_hosts user@host:~$ ssh user@server The authenticity of host 'server (1.2.3.4)' can't be established. RSA key fingerprint is ff:ff:f:ff:ff:ff:ff:ff:ff:f:ff:ff:ff:ff. Are you sure you want to continue connecting (yes/no)? yes Warning: Permanently added 'server,1.2.3.4' (RSA) to the list of known hosts. user@server's password:
4 Alternatives + Submit Alt
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remove the host for the .ssh/know_host file
16ssh-keygen -R <thehost> -
6sed -i '${LINE}d' ~/.ssh/known_host
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For example, to remove line 5 from foo, type: vi +5d +wq foo
1vi +<lineNumber>d +wq <filename> -
Easily removes line #2 in ~/.ssh/known_hosts. Show Sample Output
-1perl -p -i -e 's/.*\n//g if $.==2' ~/.ssh/known_hosts
What do you think?
Any thoughts on this command? Does it work on your machine? Can you do the same thing with only 14 characters?
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ssh-keygen -R www.example.commv ~/.ssh/known_hosts ~/.ssh/known_hosts.old; sed "${LINE}d" ~/.ssh/known_hosts.old > ~/.ssh/known_hosts... because not only does ssh-keygen silently fail with the -R option on my (ooooold) system, but sed doesn't know -i either ...