4 application level gateway (alg), 5 url filtering, 6 log and alerts – Asus SL1200 User Manual

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8

Chapter 2 - Getting to Know the Internet Security Router

ASUS SL1200

Table 2.3. DoS Attacks

Type of Attack

Name of Attacks

Re-assembly attacks

Bonk, Boink, Teardrop (New Tear), Overdrop, Opentear,

Syndrop, Jolt

ICMP Attacks

Ping of Death, Smurf, Twinge

Flooders

ICMP Flooder, UDP Flooder, SYN Flooder

Port Scans

TCP XMAS Scan, TCP Null Scan, TCP SYN Scan, TCP

Stealth Scan

TCP Attacks

TCP sequence number prediction, TCP out-of sequence

attacks

Protection with PF Rules Echo-Chargen, Ascend Kill
Miscellaneous Attacks

IP Spoofing, LAND, Targa, Tentacle MIME Flood,

Winnuke, FTP Bounce, IP unaligned time stamp attack

2.4.1.4 Application Level Gateway (ALG)

Applications such as FTP, and games dynamically open connections

based on the respective application parameter. To go through the firewall

on the router, packets pertaining to an application, require a corresponding

allow rule. In the absence of such rules, the packets will be dropped by

the router's firewall. As it is not feasible to create policies for numerous

applications dynamically (without compromising security), intelligence in

the form of Application Level Gateways (ALG), is built to parse packets

for applications and open dynamic associations. The firewall provides

a number of ALGs for popular applications such as FTP, H.323, RTSP,

Microsoft Games, and SIP.

2.4.1.5 URL Filtering

A set of keywords that should not appear in the Uniform Resource Locator,

(URL such as

www.yahoo.com) can be defined. Any URL containing one

or more of these keywords will be blocked. This is a policy independent

feature. It cannot be associated to ACL rules. This feature can be

independently enabled or disabled, but works only if firewall is enabled.

2.4.1.6 Log and Alerts

Events in the network, which could affect its security, are recorded in the

router's System log file. Event details are recorded in the WebTrends

Enhanced Log Format (WELF) format so that statistical tools can be

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