Damien Miller | a7cafae | 1999-11-16 08:02:27 +1100 | [diff] [blame] | 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 |
| 3 | mind while upgrading: |
| 4 | |
| 5 | 1. OpenSSH does not support any patented transport algorithms. |
| 6 | |
| 7 | Only 3DES and Blowfish can be selected. This difference may manifest |
| 8 | itself in the ssh command refusing to read its config files. |
| 9 | |
| 10 | Solution: Edit /etc/ssh/ssh_config and select a different "Cipher" |
| 11 | option ("3des" or "blowfish"). |
| 12 | |
| 13 | 2. Old versions of commercial SSH encrypt host keys with IDEA |
| 14 | |
| 15 | The old versions of SSH used a patented algorithm to encrypt their |
| 16 | /etc/ssh/ssh_host_key |
| 17 | |
| 18 | This problem will manifest as sshd not being able to read its host |
| 19 | key. |
| 20 | |
| 21 | Solution: You will need to run the *commercial* version of ssh-keygen |
| 22 | on the host's private key: |
| 23 | |
| 24 | ssh-keygen -u /etc/ssh/ssh_host_key |
| 25 | |
| 26 | 3. Incompatible changes to sshd_config format. |
| 27 | |
| 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. |
| 30 | |
| 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 |
| 34 | page for details. |
| 35 | |