ssh protocol version

[Wimo]

in /etc/ssh/sshd_config:

'Protocol 2' is good

'Protocol 2,1' is bad

But what the heck does '#Protocol 2,1' mean? If you comment out the line saying which versions are allowed, does that allow ANY version, or theoretically NO version?

[kac2 · Accepted solution]

i think its saying that you can use either verstion 1 or 2. you would want to use 2 only

[geddam]

Protocol 2,1 will not work...These are two different protocols defined. Protocol 1 has died in 2003 itself, by default in ESX it will be set to 2.

Thanks,,

Ramesh. Geddam,

VCP 3&4, MCTS(Hyper-V), SNIA SCP.

Please award points, if helpful

[Wimo]

Protocol 2,1 does indeed work, and lets you use either. But so does the same line commented out. That's kind of weird. I tested by setting putty to use only version 1 and it connected to one of these hosts but gave me an error on one configured for version 2 only.

Thanks guys.

[MentholMoose]

If you comment out a keyword in sshd_config the default is used, which is "Protocol 2,1". Version 1 is not desired so VMware added "Protocol 2" to only allow version 2.

Check the sshd_config man page.

Protocol

Specifies the protocol versions sshd(8) supports. The possible values are ‘1’ and ‘2’.

Multiple versions must be comma-separated. The default is “2,1”. Note that the order of

the protocol list does not indicate preference, because the client selects among multiple

protocol versions offered by the server. Specifying “2,1” is identical to “1,2”.