The Security Tab - Firewall - Linksys WRT54GS User Manual

Wireless-G Broadband Router with SpeedBooster
Beacon Interval. The default value is 100. Enter a value between 1 and 65,535 milliseconds. The Beacon Interval value
indicates the frequency interval of the beacon. A beacon is a packet broadcast by the Router to synchronize the wireless
network.
DTIM Interval. This value, between 1 and 255, indicates the interval of the Delivery Traffic Indication Message (DTIM). A DTIM
field is a countdown field informing clients of the next window for listening to broadcast and multicast messages. When the
Router has buffered broadcast or multicast messages for associated clients, it sends the next DTIM with a DTIM Interval value.
Its clients hear the beacons and awaken to receive the broadcast and multicast messages. The default value is 1.
Fragmentation Threshold. This value specifies the maximum size for a packet before data is fragmented into multiple
packets. If you experience a high packet error rate, you may slightly increase the Fragmentation Threshold. Setting the
Fragmentation Threshold too low may result in poor network performance. Only minor reduction of the default value is
recommended. In most cases, it should remain at its default value of 2346.
RTS Threshold. Should you encounter inconsistent data flow, only minor reduction of the default value, 2347, is
recommended. If a network packet is smaller than the preset RTS threshold size, the RTS/CTS mechanism will not be enabled.
The Router sends Request to Send (RTS) frames to a particular receiving station and negotiates the sending of a data frame.
After receiving an RTS, the wireless station responds with a Clear to Send (CTS) frame to acknowledge the right to begin
transmission. The RTS Threshold value should remain at its default value of 2347.
Change these settings as described here and click the Save Settings button to apply your changes or Cancel Changes to
cancel your changes.

The Security Tab - Firewall

Firewall Protection. Enable this feature to employ Stateful Packet Inspection (SPI) for more detailed review of data packets
entering your network environment.
Block WAN Requests. Enable the Block WAN Request feature by checking the box beside Block Anonymous Internet
Requests and you can prevent your network from being "pinged," or detected, by other Internet users. The Block WAN
Request feature also reinforces your network security by hiding your network ports. Both functions of the Block WAN Request
feature make it more difficult for outside users to work their way into your network. This feature is enabled by default. Select
Disabled to allow anonymous Internet requests.
Filter Multicast. Multicasting allows for multiple transmissions to specific recipients at the same time. If multicasting is
permitted, then the Router will allow IP multicast packets to be forwarded to the appropriate computers. Select Enabled to
filter multicasting, or Disabled to disable this feature.
Filter Internet NAT Redirection. This feature uses port forwarding to block access to local servers from local networked
computers. Select Enabled to filter Internet NAT redirection, or Disabled to disable this feature.
Filter IDENT (Port 113). This feature keeps port 113 from being scanned by devices outside of your local network. Select
Enabled to filter port 113, or Disabled to disable this feature.
Change these settings as described here and click the Save Settings button to apply your changes or Cancel Changes to
cancel your changes.
Chapter 3: Configuring the Wireless-G Broadband Router
The Security Tab - Firewall
fragmentation: breaking a packet into smaller units when
transmitting over a network medium that cannot support
the original size of the packet.
Figure 3-29: Security Tab - Firewall
firewall: a set of related programs located at a network
gateway server that protects the resources of a network
from users from other networks.
vpn: a security measure to protect data as it leaves one
network and goes to another over the Internet
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