ZyXEL Communications ZyWall USG 2000 User Manual page 519

Snort Signatures
You may want to refer to open source Snort signatures when creating custom
ZyWALL 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 ZyWALL.
Table 154 ZyWALL - Snort Equivalent Terms
ZYWALL 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
ZyWALL USG 2000 User's Guide
SNORT EQUIVALENT TERM
tos
id
fragbits
fragoffset
ttl
ipopts
sameip
(In Snort rule header)
flow
flags
seq
ack
window
(In Snort rule header)
Chapter 31 IDP
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