/.ssh/known_hosts ownership

Smoot Carl-Mitchell smoot at tic.com
Thu May 22 05:03:23 UTC 2008

On Wed, 2008-05-21 at 19:49 -0700, NoOp wrote:
> Following the flurry of ssh updates recently, I notice that my
> /.ssh/known_hosts is set to root.
> Now, in order to get NX and a few other ssh related programs to work
> I've had to reset the ownership to my user & group.
> My question: is resetting /.ssh/known_hosts to user vs root a security
> issue?

No it is not.  It should be owned by your user id.  known_hosts stores
the host keys collected from remote servers.  If the remote key changed,
it may mean the remote server has been compromised or a person in the
middle attack is underway. In most cases the host key has changed
because it has been regenerated on the remote system.  For the truly
paranoid it is a useful check.  Some admins require the know_host key to
match before allowing an SSH connection.  This is handled by the
StrictHostKeyChecking keyword. When set to "yes", it requires you to add
remote host keys manually.
Smoot Carl-Mitchell
System/Network Architect
smoot at tic.com
+1 480 922 7313
cell: +1 602 421 9005

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