1 OpenSSH is almost completely compatible with the commercial SSH 1.2.x.
2 There are, however, a few exceptions that you will need to bear in
5 1. OpenSSH does not support any patented transport algorithms.
7 Only 3DES and Blowfish can be selected. This difference may manifest
8 itself in the ssh command refusing to read its config files.
10 Solution: Edit /etc/ssh/ssh_config and select a different "Cipher"
11 option ("3des" or "blowfish").
13 2. Old versions of commercial SSH encrypt host keys with IDEA
15 The old versions of SSH used a patented algorithm to encrypt their
18 This problem will manifest as sshd not being able to read its host
21 Solution: You will need to run the *commercial* version of ssh-keygen
22 on the host's private key:
24 ssh-keygen -u /etc/ssh/ssh_host_key
26 3. Incompatible changes to sshd_config format.
28 OpenSSH extends the sshd_config file format in a number of ways. There
29 is currently one change which is incompatible with the old.
31 Commercial SSH controlled logging using the "QuietMode" and
32 "FascistLogging" directives. OpenSSH introduces a more general set of
33 logging options "SyslogFacility" and "LogLevel". See the sshd manual