4.27 The Bugs and More Bugs panels

Not all SSH servers work properly. Various existing servers have bugs in them, which can make it impossible for a client to talk to them unless it knows about the bug and works around it.

Since most servers announce their software version number at the beginning of the SSH connection, PuTTY will attempt to detect which bugs it can expect to see in the server and automatically enable workarounds. However, sometimes it will make mistakes; if the server has been deliberately configured to conceal its version number, or if the server is a version which PuTTY's bug database does not know about, then PuTTY will not know what bugs to expect.

The Bugs and More Bugs panels (there are two because we have so many bug compatibility modes) allow you to manually configure the bugs PuTTY expects to see in the server. Each bug can be configured in three states:

• ‘Off’: PuTTY will assume the server does not have the bug.
• ‘On’: PuTTY will assume the server does have the bug.
• ‘Auto’: PuTTY will use the server's version number announcement to try to guess whether or not the server has the bug.

• 4.27.1 ‘Chokes on SSH-1 ignore messages’
• 4.27.2 ‘Refuses all SSH-1 password camouflage’
• 4.27.3 ‘Chokes on SSH-1 RSA authentication’
• 4.27.4 ‘Chokes on SSH-2 ignore messages’
• 4.27.5 ‘Chokes on PuTTY's SSH-2 ‘winadj’ requests’
• 4.27.6 ‘Miscomputes SSH-2 HMAC keys’
• 4.27.7 ‘Miscomputes SSH-2 encryption keys’
• 4.27.8 ‘Requires padding on SSH-2 RSA signatures’
• 4.27.9 ‘Misuses the session ID in SSH-2 PK auth’
• 4.27.10 ‘Handles SSH-2 key re-exchange badly’
• 4.27.11 ‘Ignores SSH-2 maximum packet size’
• 4.27.12 ‘Replies to requests on closed channels’
• 4.27.13 ‘Only supports pre-RFC4419 SSH-2 DH GEX’