Good suggestion, not sure if this helps anyone.

This is trying to ssh to the live boot Knoppix 5.1.1 ( Current Linux Mag Cover disk. Issue 77 )
Trying from DamnSmall Linux:
root@0[root]# ssh -v 10.1.0.44
OpenSSH_3.6.1p2 Debian 1:3.6.1p2-9, SSH protocols 1.5/2.0, OpenSSL 0x0090705f
debug1: Reading configuration data /etc/ssh/ssh_config
debug1: Applying options for *
debug1: /etc/ssh/ssh_config line 17: Deprecated option "FallBackToRsh"
debug1: /etc/ssh/ssh_config line 18: Deprecated option "UseRsh"
debug1: Rhosts Authentication disabled, originating port will not be trusted.
debug1: Connecting to 10.1.0.44 [10.1.0.44] port 22.
debug1: Connection established.
debug1: read PEM private key done: type DSA
debug1: read PEM private key done: type RSA
debug1: identity file /root/.ssh/identity type -1
debug1: identity file /root/.ssh/id_rsa type -1
debug1: identity file /root/.ssh/id_dsa type -1

Try to go from Knoppix back back to the DamnSmall linux machine:
# ssh -v 10.1.0.10
Basically the lines with errors are:
debug1: An invalid name was supplied
Cannot determine realm for numeric host address

debug1: An invalid name was supplied
A parameter was malformed
Validation error

debug1: SSH2_MSG_KEXINIT sent
-----------------------------------------------------------

Giving the machines names in /etc/hosts made no difference.