Managing iptables drop lists

I've talked about my Logdropper script before. While making some changes to that script, I screwed up and accidentally blocked far more addresses than I wanted to. I could have just reset iptables entirely or rebooted, but I only wanted to get rid of the ones I just added.

Bash brace expansion helped me out (see Bash 3.00 brace expansion and Bash Brace Expansion). I can get a list of DROPS easily:

# /sbin/iptables --list -n --line-numbers | grep DROP 
5    DROP       all  --  209.51.197.0/24      0.0.0.0/0           
6    DROP       all  --  103.6.213.150        0.0.0.0/0           
7    DROP       all  --  148.251.184.96       0.0.0.0/0           
8    DROP       all  --  148.251.187.69       0.0.0.0/0           
9    DROP       all  --  173.209.49.90        0.0.0.0/0           
10   DROP       all  --  173.45.125.154       0.0.0.0/0           
11   DROP       all  --  209.190.6.194        0.0.0.0/0           
12   DROP       all  --  213.241.67.51        0.0.0.0/0           
13   DROP       all  --  49.50.69.30          0.0.0.0/0           
14   DROP       all  --  5.101.146.50         0.0.0.0/0           
15   DROP       all  --  62.210.245.47        0.0.0.0/0           
16   DROP       all  --  62.212.73.131        0.0.0.0/0           
17   DROP       all  --  68.168.114.42        0.0.0.0/0           
18   DROP       all  --  88.150.131.58        0.0.0.0/0           
19   DROP       all  --  94.229.76.218        0.0.0.0/0           
20   DROP       all  --  95.141.32.156        0.0.0.0/0     
 

I knew that the new rules started at line 8. You delete rules with "iptables -D INPUT linenumber" (assuming your DROPS are in the INPUT chain, see Understanding IPTABLES). Obviously it would be tedious to do that manually, so we will use brace expansion. However, we can't say "for i in {8..20}" because the lines will renumber after each command. Fortunately, Bash doesn't object to counting down:

for i in {20..8}; 
do iptables -D INPUT $i
done
 

Simple, right?

Got something to add? Send me email.

More Articles by Anthony Lawrence

Find me on Google+

© 2015-05-05 Anthony Lawrence

---

Printer Friendly Version

Site map     |      Disclaimer

Managing iptables drop lists Copyright © May 2015 Tony Lawrence

Have you tried Searching this site?

Support Rates

This is a Unix/Linux resource website. It contains technical articles about Unix, Linux and general computing related subjects, opinion, news, help files, how-to's, tutorials and more.

Contact us

Printer Friendly Version