2

I'm trying to get over the /var/log/secure log file, and show only the "Failed Password" log type, which appear at least 3 times.. There is any way to do that using linux commands only? awk? grep?

An example for secure log,

Mar 20 08:38:28 localhost sshd[21895]: pam_unix(sshd:auth): authentication failure; logname= uid=0 euid=0 tty=ssh ruser= rhost=mail.queued.net user=root 
Mar 20 08:38:31 localhost sshd[21895]: Failed password for root from 207.210.101.209 port 2854 ssh2 
Mar 20 15:38:31 localhost sshd[21896]: Received disconnect from 207.210.101.209: 11: Bye Bye 
Mar 20 08:38:32 localhost unix_chkpwd[21900]: password check failed for user (root) 
Mar 20 08:38:32 localhost sshd[21898]: pam_unix(sshd:auth): authentication failure; logname= uid=0 euid=0 tty=she

from this log file I expect say nothing because there is only 1 Failed Password line, but lets say there were 4 lines of "Failed Password", with the same IP - I want to display the IP address which probably trying to brute force me..

  • 1
    can you post the sample contents or /var/log/secure log file – Kamaraj Dec 9 '16 at 16:57
0

This is just a way to do the job. Instead of username, I prefer count how many times a specific IP address try to connect to my host, because then I can eventually ban it.

awk '/Failed password/{ z[$11]++; } 
     END{ 
       for (i in z){ 
         if (z[i]>3) printf("%s attemps %s times.\n", i, z[i])
       }
}' /var/log/secure

(Of course it can be a oneliner command, I indented to increase readability.)

Explanation:

awk reads the log file line by line. If a line contain the string /Failed password/ increment an array element z[$11]++ index by $11 (i.e. the IP address): I use this as a counter. At the end, search in the array z[$11] and print only the IP addresses that have tried to connect more than 3 times.
You can customize the check and the print message as you like.


If your concern are the brute-force attempts, may I suggest you to use an existing tool as Fail2ban which scans log files and bans IPs that show the malicious signs (for examples: too many password failures, seeking for exploits, etc..). It's easy to understand and configure to fit your needs.

  • Can you please explain your solution? Thank you for your help! – J.Dog Dec 9 '16 at 23:30
  • Hi, I'm trying to execute that script via subprocess as you can see : p=subprocess.Popen(["awk '/Failed password/' {z[$8]++;}END {printf("lala")}' secure"],stdout=subprocess.PIPE,shell=True) and I'm getting syntax error. Every thing works fine, except for the print inside the END { }, What I'm doing wrong? – J.Dog Dec 11 '16 at 1:23
0
$ awk '/Failed password/{for(i=1;i<=NF;i++)if($i~/for/)user[$(i+1)]++}END{for(j in user){if(user[j]>3){printf("%s : %s times failed\n",j,user[j])}}}' /var/log/secure
  • If I understand the question correctly, then I think, your answer does not do, what OP is asking for. – Alex Stragies Dec 9 '16 at 17:58
  • can you explain what OP is asking for ? if you have sample contents of secure file, can you post... – Kamaraj Dec 9 '16 at 18:01
  • /var/log/secure holds lines like "DATE HOST DAEMON: Failed Password for user kamaraj ip 12.34.56.78 port 3456". (I think) he wants the usernames/IPs, that have tried/failed 3 times or more. – Alex Stragies Dec 9 '16 at 18:07
  • hmm.. lets wait for OP to provide the exact requirement and example file contents... – Kamaraj Dec 9 '16 at 18:08
  • Yeah, I'm also waiting for clarification. – Alex Stragies Dec 9 '16 at 18:10

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

Not the answer you're looking for? Browse other questions tagged or ask your own question.