Message: "Corrupted MAC on input", when connecting to Windows SSH server

Troubleshooting

Problem

Corrupted MAC on input.
ssh_dispatch_run_fatal: Connection to <remote_ip_address> port 22: message authentication code incorrect

This occurred when connecting to Windows SSH server.

Cause

The problem is due to the MAC: umac-128-etm@openssh.com that was negotiated between the IBM i and the Windows server. Both use different SSH processing.

Resolving The Problem

Specify the MAC hmac using the -m option.

Example:

ssh -T -vvv -m hmac-sha2-256-etm@openssh.com remoteuserid@remotehost

or without verbose output:

ssh -T -m hmac-sha2-256-etm@openssh.com remoteuserid@remotehost

Document Location

Worldwide

[{"Type":"MASTER","Line of Business":{"code":"LOB68","label":"Power HW"},"Business Unit":{"code":"BU070","label":"IBM Infrastructure"},"Product":{"code":"SWG60","label":"IBM i"},"ARM Category":[{"code":"a8m0z0000000CKoAAM","label":"Communications-\u003ESFTP and SSH or Secure Shell"}],"ARM Case Number":"","Platform":[{"code":"PF025","label":"Platform Independent"}],"Version":"All Versions"}]

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Document Information

More support for:
IBM i

Component:
Communications->SFTP and SSH or Secure Shell

Software version:
All Versions

Document number:
7148312

Modified date:
07 May 2024

UID

ibm17148312

IBM Support

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