flex-fw: snat function

snat

Translate source address for connections specifed by filter

Syntax

snat help | [action ACTION] [CHAIN] [FILTER] to-addr NEW_SOURCE

ACTION := insert | append | delete

Change the default action defined in the file /etc/flex-fw/vars/base/action (usually append)

CHAIN := postrouting | chain IPTABLES_CHAIN

Iptables chain for adding new rules.

Default: postrouting

FILTER := [FROM] [TO] [proto PROTO]

NEW_SOURCE := [IPADDR[-IPADDR]][:PORT_NUMBER[-PORT_NUMBER]]

IPv4 address or IPv4 address and port

FROM := src IPADDR

Source part of filter (only IP address is allowed, no interface).

TO := out-if IFACE] | dst IPADDR

| to ZONE

Destination part of filter.

PROTO := any | { tcp [SOURCE_PORT] [DESTINATION_PORT] } | { udp [SOURCE_PORT] [DESTINATION_PORT] } | PROTO_NUMBER

Network protocol and some rlated info.

IFACE := any | INTERFACE_NAME

Network interface name. any is a synonym for +.

IPADDR := any | IPv4_ADDRESS

IPv4 host or network address. For example: 192.168.0.12, 192.168.0.0/16. any is a synonym for 0.0.0.0/0.

ZONE := name of zone described in the file /etc/flex-fw/zones/zonename

The zonename file contains lines with interface name and IPv4 address per each line and divided by spaces. Look to zones for details.

SOURCE_PORT := sport PORT | sports PORT,PORT,...

Source port(s) for TCP or UDP protocol.

DESTINATION_PORT := dport PORT | dports PORT,PORT,...

Destination port(s) for TCP or UDP protocol.

PORT := any | priv | unpriv | PORT_NUMBER | PORT_NUMBER:PORT_NUMBER

Port of TCP or UDP protocol. any is equal 0:65535. priv is equal 0:1023. unpriv is equal 1024:65535.

PROTO_NUMBER := the numeric value specified in /etc/protocols.

Examples

Translate source IP and forward a few connections from LAN to Internet

snat to-addr $ipWan1 src $netLan1 out-if $ifWan1
allow forward in-if $ifLan1 src $netLan1 out-if $ifWan1 proto icmp
allow forward in-if $ifLan1 src $netLan1 out-if $ifWan1 proto tcp dports 22,25,80,110,143,443