SSHD Connection Errors After Upgrading To Exadata Version 220.127.116.11.0
Last updated on FEBRUARY 21, 2013
Applies to:Enterprise Manager for Oracle Database - Version 18.104.22.168.0 to 22.214.171.124.0 [Release 12.1]
Information in this document applies to any platform.
Oracle Exadata Image Version 126.96.36.199.0
Discovery of Exadata environment fails while running the Exadata DB Machine Discovery wizard at the login verification step (encountered just after adding the agent and storage cell credentials) with the following message:
<cell name> - Failed to launch process: Algorithm negotiation fail
In addition, the following messages will be logged in /var/log/secure on the storage cell:
Mar 12 03:29:53 ****cel01 sshd: Connection from *.*.*.* port 9739
Mar 12 03:29:53 ****cel01 sshd: fatal: no matching cipher found:
For an already discovered Exadata environment, while metrics will still be collected, no administrative operations can be performed.
The root cause of this issue are additional security changes made in the latest Exadata release. The Exadata changes are driven by security standards defined in RFC 4344 on ssh (section 6.2). These standards list 'counter mode encryption' as a more secure method for ssh communication.
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