The default list command, iptables -L [<chain-name>], provides a very basic overview of the default filter table's current chains. Additional options provide more information:
-v — Displays verbose output, such as the number of packets and bytes each chain has processed, the number of packets and bytes each rule has matched, and which interfaces apply to a particular rule.
-x — Expands numbers into their exact values. On a busy system, the number of packets and bytes processed by a particular chain or rule may be abbreviated to Kilobytes, Megabytes (Megabytes) or Gigabytes. This option forces the full number to be displayed.
-n — Displays IP addresses and port numbers in numeric format, rather than the default hostname and network service format.
--line-numbers — Lists rules in each chain next to their numeric order in the chain. This option is useful when attempting to delete the specific rule in a chain or to locate where to insert a rule within a chain.
-t <table-name> — Specifies a table name. If omitted, defaults to the filter table.
The following examples illustrate the use of several of these options. Note the difference in the byte display by including the -x option.
[root@myserver ~]# iptables -L OUTPUT -v -n -x Chain OUTPUT (policy ACCEPT 64005 packets, 6445791 bytes) pkts bytes target prot opt in out source destination 1593 133812 ACCEPT icmp -- * * 0.0.0.0/0 0.0.0.0/0 [root@myserver ~]#iptables -L OUTPUT -v -n Chain OUTPUT (policy ACCEPT 64783 packets, 6492K bytes) pkts bytes target prot opt in out source destination 1819 153K ACCEPT icmp -- * * 0.0.0.0/0 0.0.0.0/0 [root@myserver ~]#