From c028b9979836c64764bebde8c330680952d0ece4 Mon Sep 17 00:00:00 2001 From: Tad Date: Wed, 28 Jun 2017 12:30:56 -0400 Subject: [PATCH] Harden network via iptables Change-Id: I42392ed3dcd7d2f42c312bb36f65ccb12914d13b --- server/CommandListener.cpp | 35 +++++++++++++++++++++++++++++++++++ 1 file changed, 35 insertions(+) diff --git a/server/CommandListener.cpp b/server/CommandListener.cpp index b16da18..2fcc696 100755 --- a/server/CommandListener.cpp +++ b/server/CommandListener.cpp @@ -230,6 +230,41 @@ CommandListener::CommandListener() : createChildChains(V4, "nat", "PREROUTING", NAT_PREROUTING); createChildChains(V4, "nat", "POSTROUTING", NAT_POSTROUTING); + + //Drop invalid packets + execIptables(V4V6, "-w", "-I", "INPUT", "-m", "conntrack", "--ctstate", "INVALID", "-j", "DROP", NULL); + execIptables(V4V6, "-w", "-I", "OUTPUT", "-m", "conntrack", "--ctstate", "INVALID", "-j", "DROP", NULL); + //execIptables(V4V6, "-w", "-I", "FORWARD", "-m", "conntrack", "--ctstate", "INVALID", "-j", "DROP", NULL); + //Credit: https://javapipe.com/iptables46-ddos-protection + //Drop TCP packets that are new and are not SYN + execIptables(V4V6, "-w", "-t", "raw", "-A", "PREROUTING", "-p", "tcp", "!", "--syn", "-m", "conntrack", "--ctstate", "NEW", "-j", "DROP", NULL); + //Drop SYN packets with suspicious MSS value + execIptables(V4, "-w", "-t", "raw", "-A", "PREROUTING", "-p", "tcp", "-m", "conntrack", "--ctstate", "NEW", "-m", "tcpmss", "!", "--mss", "536:65535", "-j", "DROP", NULL); + execIptables(V6, "-w", "-t", "raw", "-A", "PREROUTING", "-p", "tcp", "-m", "conntrack", "--ctstate", "NEW", "-m", "tcpmss", "!", "--mss", "1220:65535", "-j", "DROP", NULL); + //Drop packets with bogus TCP flags + execIptables(V4V6, "-w", "-t", "raw", "-A", "PREROUTING", "-p", "tcp", "--tcp-flags", "FIN,SYN,RST,PSH,ACK,URG", "NONE", "-j", "DROP", NULL); + execIptables(V4V6, "-w", "-t", "raw", "-A", "PREROUTING", "-p", "tcp", "--tcp-flags", "FIN,SYN", "FIN,SYN", "-j", "DROP", NULL); + execIptables(V4V6, "-w", "-t", "raw", "-A", "PREROUTING", "-p", "tcp", "--tcp-flags", "SYN,RST", "SYN,RST", "-j", "DROP", NULL); + execIptables(V4V6, "-w", "-t", "raw", "-A", "PREROUTING", "-p", "tcp", "--tcp-flags", "SYN,FIN", "SYN,FIN", "-j", "DROP", NULL); + execIptables(V4V6, "-w", "-t", "raw", "-A", "PREROUTING", "-p", "tcp", "--tcp-flags", "FIN,RST", "FIN,RST", "-j", "DROP", NULL); + execIptables(V4V6, "-w", "-t", "raw", "-A", "PREROUTING", "-p", "tcp", "--tcp-flags", "FIN,ACK", "FIN", "-j", "DROP", NULL); + execIptables(V4V6, "-w", "-t", "raw", "-A", "PREROUTING", "-p", "tcp", "--tcp-flags", "ACK,URG", "URG", "-j", "DROP", NULL); + execIptables(V4V6, "-w", "-t", "raw", "-A", "PREROUTING", "-p", "tcp", "--tcp-flags", "ACK,FIN", "FIN", "-j", "DROP", NULL); + execIptables(V4V6, "-w", "-t", "raw", "-A", "PREROUTING", "-p", "tcp", "--tcp-flags", "ACK,PSH", "PSH", "-j", "DROP", NULL); + execIptables(V4V6, "-w", "-t", "raw", "-A", "PREROUTING", "-p", "tcp", "--tcp-flags", "ALL", "ALL", "-j", "DROP", NULL); + execIptables(V4V6, "-w", "-t", "raw", "-A", "PREROUTING", "-p", "tcp", "--tcp-flags", "ALL", "NONE", "-j", "DROP", NULL); + execIptables(V4V6, "-w", "-t", "raw", "-A", "PREROUTING", "-p", "tcp", "--tcp-flags", "ALL", "FIN,PSH,URG", "-j", "DROP", NULL); + execIptables(V4V6, "-w", "-t", "raw", "-A", "PREROUTING", "-p", "tcp", "--tcp-flags", "ALL", "SYN,FIN,PSH,URG", "-j", "DROP", NULL); + execIptables(V4V6, "-w", "-t", "raw", "-A", "PREROUTING", "-p", "tcp", "--tcp-flags", "ALL", "SYN,RST,ACK,FIN,URG", "-j", "DROP", NULL); + //Drop spoofed packets + execIptables(V4, "-w", "-t", "raw", "-A", "PREROUTING", "-s", "0.0.0.0/8", "-j", "DROP", NULL); + execIptables(V4, "-w", "-t", "raw", "-A", "PREROUTING", "-s", "127.0.0.0/8", "!", "-i", "lo", "-j", "DROP", NULL); + //Drop fragments + execIptables(V4, "-w", "-t", "raw", "-A", "PREROUTING", "-f", "-j", "DROP", NULL); + //Limit connections per source IP + execIptables(V4V6, "-w", "-A", "INPUT", "-p", "tcp", "-m", "connlimit", "--connlimit-above", "32", "!", "-i", "lo", "-j", "REJECT", NULL); + + // Let each module setup their child chains setupOemIptablesHook(); -- 2.14.1