HOWTO: fix offending key in SSH

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When you perform an ssh connection to a remote machine, the first time you will be prompted to say ‘yes’ to authenticate the remote host.
This feature is controlled by StrictHostKeyChecking parameter and it is set to yes by default. From security point of view, this option should be enable because it protects you and your system against trojan horse attacks.
Sometimes you need disabling it temporarily. To disable it you can do via console or via config file.

Via console:

$ ssh -o 'StrictHostKeyChecking no' username@remotemachine

Via config file, adding line below to /etc/ssh_config (OSX) or /etc/ssh/ssh_config (linux):

StrictHostKeyChecking no

Once you turn it on, you can solve “offending key” deleting it from ~/.ssh/know_hosts through this terminal command:

$ sed -i '19d' ~/.ssh/known_hosts

where 19 is the line containing offending key. If you have suggestions, troubles or you feel alone, comment this post! :)


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