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I've been wrestling with the issue for couple of days, but have no progress. The anomaly started suddenly a few days ago, everything worked perfectly before on Windows 10.

Problem:

Need to connect to SSH service using Putty. Pageant has the correct keys loaded, everything is open and ready for successful connection, but no connection is made - instead login is displayed.

Event log from Putty during the connection attempt:

2022-05-24 10:21:13 Looking up host "xxx.xxx.xxx.xxx" for SSH connection
2022-05-24 10:21:13 Connecting to xxx.xxx.xxx.xxx port 22
2022-05-24 10:21:13 We claim version: SSH-2.0-PuTTY_Release_0.76
2022-05-24 10:21:13 Connected to 85.222.234.103
2022-05-24 10:21:13 Remote version: SSH-2.0-OpenSSH_7.2p2 Ubuntu-4ubuntu2.10
2022-05-24 10:21:13 Using SSH protocol version 2
2022-05-24 10:21:13 No GSSAPI security context available
2022-05-24 10:21:14 Doing ECDH key exchange with curve Curve25519 and hash SHA-256 (SHA-NI accelerated)
2022-05-24 10:21:14 Server also has ecdsa-sha2-nistp256 host key, but we don't know it
2022-05-24 10:21:14 Host key fingerprint is:
2022-05-24 10:21:14 ssh-ed25519 255 SHA256:WdgxNSMaVm6pkTqBt8roWYUUgnw5H2QxAiccv5dxR1w
2022-05-24 10:21:14 Initialised AES-256 SDCTR (AES-NI accelerated) outbound encryption
2022-05-24 10:21:14 Initialised HMAC-SHA-256 (SHA-NI accelerated) outbound MAC algorithm
2022-05-24 10:21:14 Initialised AES-256 SDCTR (AES-NI accelerated) inbound encryption
2022-05-24 10:21:14 Initialised HMAC-SHA-256 (SHA-NI accelerated) inbound MAC algorithm
2022-05-24 10:21:14 Pageant is running. Requesting keys.
2022-05-24 10:21:14 Pageant has 13 SSH-2 keys

Progress:

WinSCP is able to connect to the same SSH service using Pageant keys. Also I'm able to open Putty from within WinSCP connecting successfully to the server, but not directly using Putty.

Event log produced on successful connection:

2022-05-24 10:33:48 Looking up host "xxx.xxx.xxx.xxx" for SSH connection
2022-05-24 10:33:48 Connecting to xxx.xxx.xxx.xxx port 22
2022-05-24 10:33:48 We claim version: SSH-2.0-PuTTY_Release_0.76
2022-05-24 10:33:48 Connected to xxx.xxx.xxx.xxx
2022-05-24 10:33:48 Remote version: SSH-2.0-OpenSSH_7.2p2 Ubuntu-4ubuntu2.10
2022-05-24 10:33:48 Using SSH protocol version 2
2022-05-24 10:33:48 Doing ECDH key exchange with curve Curve25519 and hash SHA-256 (SHA-NI accelerated)
2022-05-24 10:33:48 Server also has ecdsa-sha2-nistp256 host key, but we don't know it
2022-05-24 10:33:48 Host key fingerprint is:
2022-05-24 10:33:48 ssh-ed25519 255 SHA256:WdgxNSMaVm6pkTqBt8roWYUUgnw5H2QxAiccv5dxR1w
2022-05-24 10:33:48 Initialised AES-256 SDCTR (AES-NI accelerated) outbound encryption
2022-05-24 10:33:48 Initialised HMAC-SHA-256 (SHA-NI accelerated) outbound MAC algorithm
2022-05-24 10:33:48 Initialised AES-256 SDCTR (AES-NI accelerated) inbound encryption
2022-05-24 10:33:48 Initialised HMAC-SHA-256 (SHA-NI accelerated) inbound MAC algorithm
2022-05-24 10:33:48 Pageant is running. Requesting keys.
2022-05-24 10:33:48 Pageant has 13 SSH-2 keys
2022-05-24 10:33:48 Trying Pageant key #0
2022-05-24 10:33:48 Server refused our key
2022-05-24 10:33:48 Trying Pageant key #1
2022-05-24 10:33:49 Sending Pageant's response
2022-05-24 10:33:49 Access granted
2022-05-24 10:33:49 Opening main session channel
2022-05-24 10:33:50 Opened main channel
2022-05-24 10:33:50 Allocated pty
2022-05-24 10:33:50 Started a shell/command

Have tried updating/repairing/reinstalling Putty and Pageant. Also have cleaned saved sessions from registry. No progress with the problem at all.

Any ideas and help is greatly appreciated.

Kristo
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  • Aren't you running PuTTY as Admin and WinSCP not, or the other way around? – Martin Prikryl May 24 '22 at 09:29
  • No difference in the level of running the applications. – Kristo May 24 '22 at 10:25
  • Are you connecting as the same _remote_ user? – u1686_grawity May 24 '22 at 11:28
  • @user1686 From the log it looks like PuTTY hangs when asking Pageant for the keys. I do not think that remote user has any effect here. – Martin Prikryl May 24 '22 at 11:57
  • yes, the user is same – Kristo May 24 '22 at 12:00
  • Are the PuTTY and WinSCP using the exact same SSH key _(if not, load it into WinSCP's bundled `pageant` and if the same occurs, it's likely the key)_? What version is WinSCP using and does it match the version of PuTTY installed? Have you updated PuTTY to the most recent version _(if so, you may want to file a bug report and downgrade to the version WinSCP is using)_? – JW0914 May 24 '22 at 12:15
  • PuTTY and WinSCP are using the same Pageant key. WinSCP is using same version (installation) of PuTTY (v 0.76). Downgraded to 0.75 and upgraded to 0.77-pre - exactly the same situation. – Kristo May 25 '22 at 07:20

0 Answers0