In other words all ssh connections will be limited to a single host with a MAC address 00:e0:4c:f1:41:6b. Using this iptables rule we will block all incoming connections to port 22 (ssh) except host with MAC address 00:e0:4c:f1:41:6b.

Rule: iptables to accept incoming ssh connections from specific MAC address.# iptables -A INPUT -p tcp -dport ssh -j REJECT # iptables -A INPUT -p tcp -s 77.66.55.44 -dport ssh -j ACCEPT What this means is that only host with IP 77.66.55.44 will be able to ssh. Using this iptables rule we will block all incoming connections to port 22 (ssh) except host with IP address 77.66.55.44. Rule: iptables to accept incoming ssh connections from specific IP address.# iptables -A INPUT -p tcp -dport ssh -j ACCEPT It will also accept connections on the loopback interface. These rules will reject all incoming connections to the server except those on port 22 (SSH). Rule: iptables to reject all incoming traffic except ssh and local connections.The difference between DROP vs REJECT is that DROP silently discards the incoming package, whereas REJECT will result in ICMP error being returned.

Note that it is possible to use REJECT instead of DROP. This iptables rule will DROP all incoming ping requests. Rule: iptables to drop incoming ping requests.More importantly this will also include current ongoing established connections. This rule will drop and block all network connection whether incoming or outgoing. Rule: iptables to reject all network connections.# iptables -A INPUT -m state -state ESTABLISHED -j ACCEPT Rule: iptables to reject all incoming network connections.# iptables -A OUTPUT -m state -state ESTABLISHED -j ACCEPT This is very useful when you are logged in to the server via ssh or telnet. The second line of the rules only allows current outgoing and established connections. Rule: iptables to reject all outgoing network connections.You can always change the rule order by specifying a rule number in your command. Therefore, if you have a rule to accept SSH traffic, followed by a rule to deny SSH traffic, iptables will always accept the traffic because that rule comes before the deny rule in the chain. When your system receives a packet of network traffic, iptables will match it to the first rule it can. Be aware that the order of your iptables rules matters.

Iptables list