User Guide

ISDN Router Manual V.1.1

5.7 Configure Firewall and Network Address Translation

config firewall <command> <action> <protocol> <address>

command = { add, delete, flush, zero }

action = { allow, count, deny, divert, reject, reset }

protocol = { ip, icmp, tcp, udp }

address = from { any, <IP address/netmask:port> }

to { any, <address/netmask:port> } via { any, ether, isdn }

add Add an entry to the firewall/accounting rule list

delete Delete an entry from the firewall/accounting rule list

flush This causes all entries in the firewall chain to be removed except the fixed default

policy enforced by the kernel (index 65535). Use caution when flushing rules, the

default deny policy will leave your system cut off from the network until allow

entries are added to the chain.

zero <index>When used without an index argument, all packet counters are cleared. If an index is

supplied, the clearing operation only affects a specific chain entry.

reject Drop the packet, and send an ICMP host or port unreachable (as appropriate) packet

to the source.

allow Pass the packet on as normal. (aliases: pass and accept)

deny Drop the packet. The source is not notified via an ICMP message (thus it appears

that the packet never arrived at the destination).

count Update packet counters but do not allow/deny the packet based on this rule.The

search continues with the next chain entry.

all Matches any IP packet

icmp Matches ICMP packets

tcp Matches TCP packets