Fortinet IPS manual UDP header keywords Keyword and Value Description

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Creating custom signatures

Custom signatures

Table 7: UDP header keywords

	Keyword and Value	Description

	--dst_port [!]{<port_int>	The destination port number.
	:<port_int> <port_int>:	You can specify a single port or port range:
	<port_int>:<port_int>};	• <port_int> is a single port.
		• :<port_int> includes the specified port and
			all lower numbered ports.
		• <port_int>: includes the specified port and
			all higher numbered ports.
		• <port_int>:<port_int> includes the two
			specified ports and all ports in between.
	--src_port [!]{<port_int>	The source port number.
	:<port_int> <port_int>:	You can specify a single port or port range:
	<port_int>:<port_int>};	• <port_int> is a single port.
		• :<port_int> includes the specified port and
			all lower numbered ports.
		• <port_int>: includes the specified port and
			all higher numbered ports.
		• <port_int>:<port_int> includes the two
			specified ports and all ports in between.
Table 8: ICMP keywords

	Keyword and Value	Usage

	--icmp_code <code_int>;	Specify the ICMP code to match.
	--icmp_id <id_int>;	Check for the specified ICMP ID value.
	--icmp_seq <seq_int>;	Check for the specified ICMP sequence value.
	--icmp_type <type_int>;	Specify the ICMP type to match.
Table 9: Other keywords

	Keyword and Value		Description

	--data_size {<size_int>		Test the packet payload size. With data_size
	<<size_int> ><size_int>		specified, packet reassembly is turned off
	<port_int><><port_int>};		automatically. So a signature with data_size
	<port_int><><port_int>};		and only_stream values set is wrong.
			and only_stream values set is wrong.
			• <size_int> is a particular packet size.
			• <<size_int> is a packet smaller than the
			specified size.
			• ><size_int> is a packet larger than the
			specified size.
			• <size_int><><size_int> within the
			range between the specified sizes.
	--data_at <offset_int>[,		Verify that the payload has data at a specified
	relative];		offset, optionally looking for data relative to the
			end of the previous content match.

	FortiGate IPS User Guide Version 3.0 MR7
32	01-30007-0080-20080916

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Contents E R G U I D E Trademarks Contents Protocol decoders IPS sensorsDoS sensors SYN flood attacksIntroduction FortiGate IPSAbout this document Fortinet documentationDocument conventions Typographic conventionsFortiGate Pptp VPN User Guide Comments on Fortinet technical documentation Customer service and technical supportFortinet Knowledge Center This section contains the following topics IPS overview and general configurationIPS settings and controls When to use IPS Default signature and anomaly settingsDefault fail open setting Config ips global Set fail-open enable disable endSetting the buffer size Configuring logging and alert emailMonitoring the network and dealing with attacks Controlling sessionsAttack log messages Signature Anomaly FortiGuard CenterUsing IPS sensors in a protection profile Creating a protection profile that uses IPS sensorsAdding protection profiles to firewall policies Select Create NewAdding protection profiles to user groups Using IPS sensors in a protection profile Viewing the predefined signature list Predefined signaturesIPS predefined signatures Settings EnableColumn Clear All FiltersCreate a sensor and add IPS filters to it Viewing the predefined signature list Viewing the custom signature list Custom signaturesIPS custom signatures Custom signature configuration Adding custom signatures using the web-based managerAdding custom signatures using the CLI Command syntax patternShows the valid characters for custom signature fields Creating custom signaturesCustom signature fields Custom signature syntax AttackidName BufferOverflow SrcportContent keywords Keyword and value Description Deprecated, see pattern and context keywords Pattern GET Context uriPattern yahoo.com Context hostPcre Regex/mdelimRegexdelimismxAEGRU Uri !uristrProtocol tcp IP header keywords Keyword and Value DescriptionTCP header keywords Keyword and Value Description Tcpflags AP Tcpflags S,12Other keywords Keyword and Value Description UDP header keywords Keyword and Value DescriptionIcmp keywords Keyword and Value Usage Sbid --name Block.example.com Example 1 signature to block access to example.comExample custom signatures Sbid --name Block.example.com Sbid --name Block.SMTP.VRFY.CMD --pattern vrfy Example 2 signature to block the Smtp ‘vrfy’ commandSbid --name Block.SMTP.VRFY.CMD Creating custom signatures Upgrading the IPS protocol decoder list Protocol decodersProtocol decoders Viewing the protocol decoder list Protocol decoder list Protocols Protocol decoder names PortAlldefault AlldefaultpassIPS sensors Viewing the IPS sensor listConfiguring IPS sensors Adding an IPS sensorProtectclient ProtectemailserverIPS sensor attributes IPS sensor filtersConfiguring filters ResetIPS sensor overrides Delete and Edit Delete or edit the filter IconsConfiguring pre-defined and custom overrides ApplicationExempt IP SourceDoS sensors Configuring DoS sensors Viewing the DoS sensor listSequence in which the sensors examine network traffic Appears, and select OKAnomaly configuration DoS sensor attributesName Enter or change the DoS sensor name Comments Will appear in the DoS sensor listUnderstanding the anomalies Anomaly Description Tcpdstsession UdpfloodUdpscan UdpsrcsessionUnderstanding the anomalies How SYN floods work What is a SYN flood attack?SYN flood attacks What is SYN threshold? What is SYN proxy?FortiGate IPS Response to SYN flood attacks How IPS works to prevent SYN floodsIPS operation before synflood threshold is reached Configure the options for tcpsynflood Select OK Configuring SYN flood protectionSuggested settings for different network conditions What is an Icmp sweep? Icmp sweep attacksHow Icmp sweep attacks work FortiGate IPS response to Icmp sweep attacksPredefined Icmp signatures Icmp sweep anomalies Configuring Icmp sweep protection Index FortiGate Version 3.0 MR7 IPS User GuideTechnical support