The conventional wisdom for several years has been that if you were using SSH (secure shell) to connect to a server from a remote client, rather than Telnet or another unsecure protocol, you were safe. However, a few vulnerabilities have been revealed recently in versions of SSH, leading some IT administrators to wonder just how secure this vital standard really is.

For example, the most recent advisory issued by the Computer Emergency Response Team (CERT) described multiple vulnerabilities in SSH implementations that could allow an attacker to usurp control of a remote server by taking advantage of a buffer overflow.

However, armed with an understanding of SSH, as well as the potential options available, system administrators should be able to make the best choice for their particular enterprise.

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