If you're like me and you work with alot of machines or frequently spin up
and teardown vagrant boxes, then your ssh config file (e.g.
is littered with entries like:
Host 192.168.1.* IdentitiesOnly yes IdentityFile ~/.ssh/id_rsa-foo Host 10.10.10.* User baz IdentitiesOnly yes IdentityFile ~/.ssh/id_rsa.bar
When the machine you'd like to ssh into falls within one of the config ip ranges, but you'd like to override the rsa key used:
$ ssh -vvv -o PubkeyAuthentication=no -o IdentitiesOnly=yes -o IdentityFile=~/.ssh/id_rsa.private firstname.lastname@example.org