Allied Telesis AT-WR4500 - Manual (Page 198)

198 AT-WR4500 Series - IEEE 802.11abgh Outdoor Wireless Routers
RouterOS v3 Configuration and User Guide
9 Firewall and QoS
9.1 Filter
Document revision: 2.7 (Fri Nov 04 1 6:04:37 G MT 2 005)
Applies to: V2.9
9.1.1
General Information
Summary
The firewall implements packet filtering and thereby provides security functions that are used to manage
data flow to, from and through the router. Along with the Network Address Translation it serve as a tool
for preventing unauthorized access to directly attached networks and the router itself as well as a filter
for outgoing traffic.
Quick Setup Guide
To add a firewall rule which drops all TCP packets that are destined to port 135 and going through the
router, use the following command:
/ip firewall filter add chain=forward dst-port=135 protocol=tcp action=drop
To deny acces to the router via Telnet (protocol TCP, port 23), type the following command:
/ip firewall filter add chain=input protocol=tcp dst-port=23 action=drop
To only allow not more than 5 simultaneous connections from each of the clients, do the following:
/ip firewall filter add chain=forward protocol=tcp tcp-flags=syn connection-limit=6,32
action=drop
Specifications
Packages required: system
License required: Level1 (P2P filters limited to 1) , Level3
Submenu level: /ip firewall filter
Standards and Technologies:
IP , RFC2113
Hardware usage: Increases with filtering rules count
Related Topics
IP Addresses and ARP
Routes, Equal Cost Multipath Routing, Policy Routing
NAT
Mangle
Packet Flow
9.1.2
Firewall Filter
Submenu level: /ip firewall filter
Description
Network firewalls keep outside threats away from sensitive data available inside the network. Whenever
different networks are joined together, there is always a threat that someone from outside of your
network will break into your LAN. Such break-ins may result in private data being stolen and distributed,
valuable data being altered or destroyed, or entire hard drives being erased. Firewalls are used as a means
of preventing or minimizing the security risks inherent in connecting to other networks. Properly
configured firewall plays a key role in efficient and secure network infrastrure deployment.