iptables
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iptables [2010/02/04 21:54] k2patel |
iptables [2011/09/22 19:26] k2patel [xt_recent] |
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| iptables -A BRTBLK -m recent --update --seconds 45 --hitcount 5 --name SSH -j DROP | iptables -A BRTBLK -m recent --update --seconds 45 --hitcount 5 --name SSH -j DROP | ||
| </code> | </code> | ||
| + | |||
| + | ==== Force SYN packets check ==== | ||
| + | Make sure NEW incoming tcp connections are SYN packets; otherwise we need to drop them: | ||
| + | |||
| + | <code bash> | ||
| + | iptables -A INPUT -p tcp ! --syn -m state --state NEW -j DROP | ||
| + | </code> | ||
| + | |||
| + | ==== Force Fragments packets check ==== | ||
| + | Packets with incoming fragments drop them. This attack result into Linux server panic such data loss. | ||
| + | |||
| + | <code bash> | ||
| + | iptables -A INPUT -f -j DROP | ||
| + | </code> | ||
| + | |||
| + | ==== XMAS packets ==== | ||
| + | Incoming malformed XMAS packets drop them: | ||
| + | |||
| + | <code bash> | ||
| + | iptables -A INPUT -p tcp --tcp-flags ALL ALL -j DROP | ||
| + | </code> | ||
| + | |||
| + | ==== Drop all NULL packets ==== | ||
| + | Incoming malformed NULL packets: | ||
| + | |||
| + | <code bash> | ||
| + | iptables -A INPUT -p tcp --tcp-flags ALL NONE -j DROP | ||
| + | </code> | ||
| + | |||
| + | |||
| + | ==== xt_recent ==== | ||
| + | |||
| + | In latest version ipt_recent replaced by xt_recent.\\ | ||
| + | there is few change which could break your iptables rules.\\ | ||
| + | In order to make ssh bruteforce protection working please use following rules.\\ | ||
| + | this also effect Fedora 15 and latest iptables / kernel | ||
| + | |||
| + | <code bash> | ||
| + | :SSH - [0:0] | ||
| + | :BRTBLK - [0:0] | ||
| + | |||
| + | |||
| + | -A INPUT -p tcp -m multiport --dports 21,22 -m recent --update --seconds 8600 --name SSH_BAN --rsource -j DROP | ||
| + | -A INPUT -p tcp -m multiport --dports 21,22 -m state --state NEW -j BRTBLK | ||
| + | |||
| + | -A SSH -m limit --limit 5/min -j LOG --log-prefix "BAD IP: " --log-level 4 | ||
| + | -A SSH -m recent --set --name SSH_BAN --rsource -j DROP | ||
| + | |||
| + | -A BRTBLK -m recent --set --name BRT --rsource | ||
| + | -A BRTBLK -m recent --update --seconds 600 --hitcount 16 --name BRT --rsource -j SSH | ||
| + | -A BRTBLK -m recent --update --seconds 60 --hitcount 4 --name BRT --rsource -j SSH | ||
| + | -A BRTBLK -j ACCEPT | ||
| + | </code> | ||
| + | |||
| + | Now try to login to box 4 times quickly to test.\\ | ||
| + | For more advanced Options please visit [[http://www.thatsgeeky.com/2011/02/escalating-consequences-with-iptables/ | Th4tsG33ky]] | ||
iptables.txt ยท Last modified: 2020/08/10 02:35 (external edit)
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