ISDN Router Manual V.1.1
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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.
a
ll
Matches any IP packet
icmp
Matches ICMP packets
tcp
Matches TCP packets
