Error from RTMT: sshd(pam_unix)[17823]

[CleverDrake]

All,

I am receiving this error from a customer's SUB. From what I can gather, this error is generated when someone tries to login to the CCM from ssh and fails. What has me worried is the volume of these errors. They have been going non-stop for a day now. Is this an attack on the network? Here is a sample of the errors:

sshd(pam_unix)[20151]: check pass; user unknown SeverityMatch - Alert sshd(pam_unix)[20170]: check pass; user unknown SeverityMatch - Alert sshd(pam_unix)[20184]: check pass; user unknown SeverityMatch - Alert sshd(pam_unix)[20197]: check pass; user unknown

[#2]

When a terminal server is connected to the serial port of a Cisco Unified Communications Manager server, the system generates a repeating alert message and corresponding syslog messages. Try to configure no exec on the lines that are connected to the console of the other devices.