When I try to ssh to machine A i get:
ssh_exchange_identification: Connection closed by remote host


but I cant ssh to other machines from A.
Why?

did you compile ssh or install it from the Debian repos ?

One of these should help..

http://www.snailbook.com/faq/libwrap-oops.auto.html

http://www.linuxquestions.org/questi...d.php?t=103423

If you are trying to connect from the local root account or to the remote root account then this will violate typical security rules.

Your firewall on either machine could be preventing the connection. Check your firewall rules to see if the required ports are being blocked by the firewall. Typical firewall rules will reject or drop any inbound connect requests.

You may have neglected to import the DSA.pub key from the local user account into the user account on the remote machine.

The key on the remote machine may be invalid.

You may have neglected to create keys at all.

There may be other reasons. These just seem to be the most likely suspects to me.