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Re: targetted SSH bruteforce attacks
From: John Jacobs <flamdugen () hotmail com>
Date: Thu, 17 Jun 2010 15:58:33 -0500



Of course it's wise to disable password authentication and just use
public key authentication.

Why?  Ssh is encrypted, so you're not exposing a password when you login.  How 
does public key authentication make you more secure (in a practical sense)?


Paul, it's more secure in that brute force attacks are mitigated because the private key is required by the client and 
the public key must appear in ~/.ssh/authorized_keys.  Disabling password authentication means a weak password on an 
account cannot be compromised by brute force or other discovery efforts.  A password on the private key provides even 
greater defense-in-depth security.

Disable password authentication and enforce key-pair authentication and targeted brute-force attacking becomes moot 
very quickly.  Moving SSHd from TCP 22 also keeps the script-kiddies and automated scanners away.

After doing these two basic things then it's time to focus on fail2ban, denyhosts, and the other firewall integrating 
solutions.


                                          
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