System information

24 221 02-FGB 101 544 Uen A - September 2008
5.2.5 DHCP Relay
The W3x terminals support DHCP relay. As a DHCP relay agent, the
terminals forward requests for IP addresses from LAN/WLAN hosts to a
DHCP server (at the ISP’s location) and then returns the IP information
from the DHCP server to the hosts.
5.2.6 SNTP
The W3x terminals include a SNTP client which provides a way to
synchronize the device’s own time of day setting with a remote NTP server.
It is possible to specify up to three (3) different SNTP servers (for fallback).
As an alternative the time can also be fetched from the mobile network (see
section Error! Reference source not found.).
5.2.7 L2TP Tunneling
The W3x terminals support one L2TP tunnel providing a mechanism for
tunneling Ethernet frames between two peers over an existing network
(usually the Internet). The LAN/WLAN is bridged into the tunnel using BCP
over PPP over L2TP.
The BCP/PPP/L2TP tunnel can be used to connect a branch office LAN to
a corporate office LAN over a 3G/HSPA network connection.
5.2.8 Firewall
The W3x terminals include a stateful packet filtering firewall (using Linux
Kernel iptables) applicable between the WAN and WLAN/LAN interfaces.
5.2.8.1 Firewall Rules
Firewall rules are used to specify matching values that a packet must have
for this rule to apply to the packet. These values include the following:
• Source or destination IP address
• Source or destination port or range of ports
• Transport protocol (UDP, TCP, IGMP, all).
• Incoming/outgoing interface
• Action; accept, drop, reject, or dscp:0xXX
Up to 50 simultaneous firewall rules can be defined and it is also possible
to use the operation ”NOT” when defining rules.
5.2.8.2 Packet Drop and Reject
A packet can be either dropped or rejected based on the outcome of the
packet classification. If the unit rejects a packet, the sender receives the
appropriate ICMP message. If the unit drops a packet, it silently discards
the packet.
5.2.8.3 Denial of Service (DoS)
A DoS attack is an attempt by an attacker to prevent legitimate hosts from
using a service. The W3x terminals support rate limit of ICMP packets (0-
2000) and TCP SYN segments (0-2000).