ZyXEL Communications ZyWall ATP series User Manual page 552

system vulnerabilities with the goal of bringing down the computer/server. Typical "network-based
intrusions" are SQL slammer, Blaster, Nimda MyDoom etc.
Snort Signatures
You may want to refer to open source Snort signatures when creating custom Zyxel Device ones. Most
Snort rules are written in a single line. Snort rules are divided into two logical sections, the rule header
and the rule options as shown in the following example:
alert tcp any any -> 192.168.1.0/24 111 (content:"|00 01 a5|"; msg:"mountd access";)
The text up to the first parenthesis is the rule header and the section enclosed in parenthesis contains the
rule options. The words before the colons in the rule options section are the option keywords.
The rule header contains the rule's:
• Action
• Protocol
• Source and destination IP addresses and netmasks
• Source and destination ports information.
The rule option section contains alert messages and information on which parts of the packet should be
inspected to determine if the rule action should be taken.
These are some equivalent Snort terms in the Zyxel Device.
Table 222 Zyxel Device - Snort Equivalent Terms
ZYXEL DEVICE TERM
Type Of Service
Identification
Fragmentation
Fragmentation Offset
Time to Live
IP Options
Same IP
Transport Protocol
Transport Protocol: TCP
Port
Flow
Flags
Sequence Number
Ack Number
Window Size
Transport Protocol: UDP
Port
Transport Protocol: ICMP
Type
Code
Chapter 30 IDP
SNORT EQUIVALENT TERM
tos
id
fragbits
fragoffset
ttl
ipopts
sameip
(In Snort rule header)
flow
flags
seq
ack
window
(In Snort rule header)
(In Snort rule header)
itype
icode
ZyWALL ATP Series User's Guide
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