etc

iptables.md

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+# Iptables.
+
+## Allow ssh traffic.
+~~~
+iptables -A INPUT -p tcp --dport=22 -j ACCEPT
+
+# -A  Append (End table) | -I Insert (Start table).
+# -p  Protocol.
+# -j  Action.
+~~~
+
+## Allow localhost traffic.
+~~~
+iptables -A INPUT -i lo -j ACCEPT
+
+# -i  Interface name.
+~~~
+
+## Allow ping.
+~~~
+iptables -A INPUT -p icmp -j ACCEPT
+~~~
+
+## Warning!!!.
+~~~
+iptables -A INPUT -m state --state ESTABLISHED,RELATED -j ACCEPT
+~~~
+
+## Input policy drop.
+~~~
+iptables -P INPUT DROP
+~~~
+
+## Save/Restore rules from file.
+~~~
+iptables-save > ./filename.rules
+
+# iptables-restore < ./filename.rules
+~~~