You should still read the
Feedback page
on the PuTTY website (also provided as
appendix B
in the manual), and follow the
guidelines contained in that.
A.7.16 Since my SSH server was upgraded to OpenSSH 3.1p1/3.4p1, I can no longer connect with PuTTY.
There is a known problem when OpenSSH has been built against an incorrect version of OpenSSL; the quick workaround is to configure PuTTY to use SSH protocol 2 and the Blowfish cipher.
For more details and OpenSSH patches, see
bug 138
in the OpenSSH BTS.
This is not a PuTTY-specific problem; if you try to connect with another client you'll likely have similar problems. (Although PuTTY's default cipher differs from many other clients.)
OpenSSH 3.1p1: configurations known to be broken (and symptoms):
•SSH-2 with AES cipher (PuTTY says ‘Assertion failed! Expression: (len & 15) == 0’ in sshaes.c, or ‘Out of memory’, or crashes)
•SSH-2 with 3DES (PuTTY says ‘Incorrect MAC received on packet’)
•SSH-1 with Blowfish (PuTTY says ‘Incorrect CRC received on packet’)
•SSH-1 with 3DES
OpenSSH 3.4p1: as of 3.4p1, only the problem with SSH-1 and Blowfish remains. Rebuild your server, apply the patch linked to from bug 138 above, or use another cipher (e.g., 3DES) instead.
Other versions: we occasionally get reports of the same symptom and workarounds with older versions of OpenSSH, although it's not clear the underlying cause is the same.
A.7.17 Why do I see ‘Couldn't load private key from ...’? Why can PuTTYgen load my key but not PuTTY?
It's likely that you've generated an SSH protocol 2 key with PuTTYgen, but you're trying to use it in an SSH-1 connection. SSH-1 and SSH-2 keys have different formats, and (at least in 0.52) PuTTY's reporting of a key in the wrong format isn't optimal.
To connect using SSH-2 to a server that supports both versions, you need to change the configuration from the default (see
question A.2.1
).
A.7.18 When I'm connected to a Red Hat Linux 8.0 system, some characters don't display properly.
A common complaint is that hyphens in man pages show up as a-acute.
With release 8.0, Red Hat appear to have made UTF-8 the default character set. There appears to be no way for terminal emulators such as PuTTY to know this (as far as we know, the appropriate escape sequence to switch into UTF-8 mode isn't sent).
A fix is to configure sessions to RH8 systems to use UTF-8 translation - see
section 4.10.1
in the documentation. (Note that if you
use ‘Change Settings’, changes may not take place immediately - see
question A.7.9
.)
If you really want to change the character set used by the server, the right place is /etc/sysconfig/i18n, but this shouldn't be necessary.
A.7.19 Since I upgraded to PuTTY 0.54, the scrollback has stopped working when I run screen.
PuTTY's terminal emulator has always had the policy that when the ‘alternate screen’ is in use, nothing is added to the scrollback. This is because the usual sorts of programs which use the alternate screen are things like text editors, which tend to scroll back and forth in the same document a lot; so (a) they would fill up the scrollback with a large amount of unhelpfully disordered text, and (b)