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Upon seeing some failure with initial ssh connections timing out; I narrowed it down to the reverse dns lookup on ssh. I've found many articles articulating how to disable the lookup; but none saying why not to...

I know I am most likely masking one problem (client host not being able to resolve in a timely manner), but I don't think I care about. Is there anything else I should be aware of? (sshd processes in question are internal facing only)

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up vote 3 down vote accepted

There is nothing "wrong" with disabling SSH reverse-DNS lookups -- I know a few people who do it routinely as a "security" measure (if you're not using the DNS server you don't have to worry if what you're getting from it is correct).

The major downside is you won't have hostnames in your SSH logs.
If you're trolling through your SSH logs because you suspect a security breach you should probably be looking up the IPs yourself anyway (from a known good DNS server, or better through an IP-to-ASN lookup), so that's probably not a big problem.

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