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Re: Unable to exchange encryption keys
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From: Daniel Stenberg via curl-users <curl-users_at_lists.haxx.se>
Date: Mon, 24 Nov 2025 23:17:52 +0100 (CET)
On Mon, 24 Nov 2025, Werner Stolz via curl-users wrote:
> We first encountered this error in 2022, and the only suggestion was to
> upgrade our version of curl. We have now done that, and the problem
> actually seems WORSE.
As you're using SFTP, I think this problem is within libssh2 and that a curl
update does almost nothing for improving this case.
> * libssh2 cryptography backend: openssl compatible
> * User: USER
> * Failure establishing ssh session: -5, Unable to exchange encryption keys
> * closing connection #0
> curl: (2) Failure establishing ssh session: -5, Unable to exchange encryption keys
This is libssh2 returning an error when it fails to establish an SSH session
with the server.
libssh2 is an understaffed and resource drained project. I propose you roll up
your sleeves and do some debugging of your own, and maybe check with other
libssh2 users if they have seen something similar.
Date: Mon, 24 Nov 2025 23:17:52 +0100 (CET)
On Mon, 24 Nov 2025, Werner Stolz via curl-users wrote:
> We first encountered this error in 2022, and the only suggestion was to
> upgrade our version of curl. We have now done that, and the problem
> actually seems WORSE.
As you're using SFTP, I think this problem is within libssh2 and that a curl
update does almost nothing for improving this case.
> * libssh2 cryptography backend: openssl compatible
> * User: USER
> * Failure establishing ssh session: -5, Unable to exchange encryption keys
> * closing connection #0
> curl: (2) Failure establishing ssh session: -5, Unable to exchange encryption keys
This is libssh2 returning an error when it fails to establish an SSH session
with the server.
libssh2 is an understaffed and resource drained project. I propose you roll up
your sleeves and do some debugging of your own, and maybe check with other
libssh2 users if they have seen something similar.
-- / daniel.haxx.se || https://rock-solid.curl.dev -- Unsubscribe: https://lists.haxx.se/mailman/listinfo/curl-users Etiquette: https://curl.se/mail/etiquette.htmlReceived on 2025-11-24