New Rule

Each chain is a list of rules which can match a set of packets. Each rule specifies what to do with a packet that matches. This is called a `target', which may be a jump to a user-defined chain in the same table. A firewall rule specifies criteria for a packet, and a target. If the packet does not match, the next rule in the chain is the examined; if it does match, then the next rule is specified by the value of the target, which can be the name of a user-defined chain or one of the special values: ACCEPT or DROP.

We recommend studying the following Linux documents before proceeding further with firewall configuration: iptables-HOWTO for basics; for more specifics please look into Bandwidth-Limiting-HOWTO, and Adv-Routing-HOWTO.

Field Definitions

Field Name | Description
Source address/mask | This is the source match which is used to match packets based on their source IP address. The main form can be used to match single IP addresses such as 192.168.1.1. It could be used with a netmask in a bits form: specify the number of ones (1's) on the left side of the network mask. This means that you could for example add /24 to use a 255.255.255.0 netmask.

Destination address/mask

This is the destination match. It is is used to match packets based on their destination address or addresses. It works pretty much the same as the source match, except that it matches based on where the packets are going. To match an IP range, you can add a netmask in the number of ones (1's) counted from the left side of the netmask bits. It would then look like 192.168.0.0/24

Policy | ACCEPT allows the packet through. DROP just drops the packet and refuses to process it any more. REJECT drops the packet, but (if it's not an ICMP packet) generates an ICMP reply to the source to tell it that the destination was unreachable.
Radio buttons to select network protocol (tcp, udp, imcp) | Set the radio button to the protocol you are creating this Rule for. For tcp or udp protocols type the source and destination ports (within the certain range, e.x. 45000:54000). For imcp protocol you should select the message type from pull down menu.