Auto detect and auto shutout password crack attempts

Posted on 2004-11-14
Last Modified: 2008-03-10
Is it at all possible to have a system that auto-detects password crack attempts and then auto-lock any further access from that IP for a period of time (configurable, so you can say that 5 failed attempts within a period of 1 minute = a crack attempt, then lock/ban that IP for 30 minute etc?)  It would obviously help to have something "sentralized" that can handle any applications' password checking, SSH, FTP, SMTP etc etc. so that all services are protected by this "time-dealy" lock?
Question by:psimation
    LVL 51

    Accepted Solution

    you either need to tell this delay each of your services (ssh, ftp, etc.), or you can use iptables with the --limit (and some other) options to detect connect requests within a given time intervall
    LVL 38

    Assisted Solution


       Password attend limitation is in
    password    required      /lib/security/ retry=5

       I'm not sure PAM can check the IP and ban it for 30 minutes.

    LVL 17

    Author Comment

    My system already has the retry=3 set, yet I still see more than 3000 attempts on root account from one source. What is the "supposed" action when retry reaches 3?
    LVL 22

    Assisted Solution

    I believe that after 3 attempts, even if you get the right password, it is ignores and treated as incorrect. Logging continues in order to help anyone trying to examine what happened at a later date.

    The reason for this is that ideally a good authentication system should never change the reaction that the attacker sees.  If the attacker starts getting any form of feedback, he knows that he has done something and can reallocaet the resources that he is using, or improve his attacking process.


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