Unable to connect to SFTP , Reason: Algorithm negotiation failed

[WaqaarAhmad]

Hi Mirth Community,

I hope you are doing well. I am reaching out for assistance with an issue we’re experiencing regarding SFTP connections in Mirth Connect.

Issue Description
We are attempting to connect our Mirth Connect server (on a Windows-based environment) to an AWS Transfer Family SFTP server. However, the connection consistently fails with the following error:

ERRORS{{ KEX_FAILURE Message="no matching key exchange method found" Kex=diffie-hellman-group1-sha1,diffie-hellman-group14-sha1,diffie-hellman-group-exchange-sha1 SourceIP=x.x.x.x}}
After investigation, we learned that AWS requires the following supported Key Exchange (KEX) algorithms:

ecdh-sha2-nistp256
ecdh-sha2-nistp384
ecdh-sha2-nistp521
diffie-hellman-group-exchange-sha256
diffie-hellman-group16-sha512
diffie-hellman-group18-sha512
diffie-hellman-group14-sha256
It appears that our current Mirth Connect SFTP setup is not configured to use these algorithms.

Environment Details
Mirth Connect Version: [3.4.2.8129]
Server OS: Windows Server [Windows 10]
SFTP Server: AWS Transfer Family (Test Server)
Steps Taken
Verified that the provided IPs and ports for the SFTP server are whitelisted on both ends.
Confirmed that traffic is allowed from inbound to outbound.
Attempted to find a "Key Exchange Algorithms" or "SSH Options" configuration in the Mirth channel destination but could not locate any such settings.
Reviewed AWS documentation on supported algorithms and confirmed our Mirth setup does not match the requirements.
Request for Assistance
Does Mirth Connect natively support these encryption algorithms? If yes, how can we configure them?
If not, are there recommended workarounds (e.g., using an external SFTP client like WinSCP and integrating it with Mirth Connect)?
Is there a way to update Mirth Connect’s underlying JSch library or SFTP client to support these algorithms?
Any guidance or suggestions would be greatly appreciated. Please let me know if you need additional details to assist further.

Waqar

[pacmano1]

So you tried values like: https://github.com/pacmano1/Mirth-Snippets/blob/main/MirthSSH_4.5.md?

You can of course call jsch from java if needed. Adapt https://github.com/pacmano1/Mirth-Snippets/blob/main/sftp_get_to_attachment_newJsch.js, which is a get, not a put.

[jonbartels]

I see in your screenshot you are using MC 3.4.2. This is a very old version of MC.

4.5.0 has this improvement - #5608

Is there a way to update Mirth Connect’s underlying JSch library or SFTP client to support these algorithms?

If you cannot upgrade - Look at these search results you can take the newer jSch JAR and swap it in Mirth and it should be compatible .

The newer jSCH may not solve your issue directly but it will provide better logging and better data about what the problem is.

If not, are there recommended workarounds (e.g., using an external SFTP client like WinSCP and integrating it with Mirth Connect)?

You can make syscalls from Mirth using this example however this is maybe not the best way to solve an SFTP issue because you have to write files and manage the data on disk rather than just sending it from MC.

[pacmano1]

Thanks @jonbartels, I missed the old version of Mirth.