Compatibility issue: OpenSSH v2.3.0p1 vs. 3.0.2: RSA keys

[Markus Friedl]

the problem is that protocol version negotiation and authentication
method negotiation are not related.

the server offers all protocol versions it supports.

then the client decides with version to use.

then client tries all available authentication methods for this
protocol.

with 'Protocol 2,1' in ssh_config the client will
always use protocol v2 if the server supports this.

at this point the client does not know what authentication
methods the server will allow. what you probably want is

	try ssh2 with pubkey
	try ssh1 with pubkey
	try ssh2 with password
	try ssh1 with password

but this won't work.
	try ssh1 with pubkey

i see no simple solution to your problem.