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Chapter 38 IDP
ZyWALL USG Series User’s Guide
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The Priority column shows warn for signatures that are configured to generate a log only. It shows critical
for signatures that are configured to generate a log and alert. All IDP signatures come under the IDP
category. The Note column displays ACCESS FORWARD when no action is configured for the signature. It
displays ACCESS DENIED if you configure the signature action to drop the packet. The destination port is
the service port (53 for DNS in this case) that the attack tries to exploit.
Figure 511 Custom Signature Log
38.4 IDP Technical Reference
This section contains some background information on IDP.
Host Intrusions
The goal of host-based intrusions is to infiltrate files on an individual computer or server in with the goal of
accessing confidential information or destroying information on a computer.
You must install a host IDP directly on the system being protected. It works closely with the operating
system, monitoring and intercepting system calls to the kernel or APIs in order to prevent attacks as well
as log them.
Disadvantages of host IDPs are that you have to install them on each device (that you want to protect)
in your network and due to the necessarily tight integration with the host operating system, future
operating system upgrades could cause problems.
Network Intrusions
Network-based intrusions have the goal of bringing down a network or networks by attacking
computer(s), switch(es), router(s) or modem(s). If a LAN switch is compromised for example, then the
whole LAN is compromised. Host-based intrusions may be used to cause network-based intrusions when
the goal of the host virus is to propagate attacks on the network, or attack computer/server operating
system vulnerabilities with the goal of bringing down the computer/server. Typical “network-based
intrusions” are SQL slammer, Blaster, Nimda MyDoom etc.