Network Management
No matching mac found Error for NCM Connections
This article provides information for the "No matching mac found" error
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Overview
This article provides information for the "No matching mac found" error in the switch logs, which is caused by the SSH Communication. Also, sometimes the switch/node gives the following error: Test Failed. Connection Refused by X.X.X.X
For connection failures, refer to NCM error: Test failed. Connection refused by x.x.x.x.
If that doesn't resolve the issue, check the logs from the switch side. There, we can observe something blocking the SSH communications.
Product section
Cause
We can observe the following Error in the switch logs:
008430: Aug 5 09:47:35: %SSH-3-NO_MATCH: No matching mac found: client hmac-sha2-256,hmac-sha2-512,hmac-sha1,hmac-sha1-96,hmac-md5,none server hmac-sha2-256-etm@openssh.com,hmac-sha2-512-etm@openssh.com
008431: Aug 5 09:47:35: %SSH-5-SSH2_SESSION: SSH2 Session request from 10.10.15.130 (tty = 2) using crypto cipher '', hmac '' Failed
This indicates that the issue is with the MAC algorithm, which didn't find the exact match for the NCM connection profiles.
This verifies that the device is not using a supported MAC algorithm that NCM is using.
Resolution
Ensure the device supports the MAC algorithms included. Start by checking the device's SSH configuration (show ip ssh) and ensuring its MAC algorithms are included. Then, adjust the MAC algorithms. If the MAC Algorithm that your device uses is not listed in the article below, please change it to one that NCM supports for it to work.
Supported algorithms and ciphers for SSH communications by NPM, NCM, and SolarWinds Platform
Once the algorithm is adjusted, NCM should pass the connection test.