Protocol decoders, IPS sensors, DoS sensors, Index | Fortinet

Creating custom signatures	23
Custom signature fields	23
Custom signature syntax	24
Example custom signatures	33
Protocol decoders	37
Protocol decoders	37
Upgrading the IPS protocol decoder list	37
Viewing the protocol decoder list	38
IPS sensors	39
Viewing the IPS sensor list	39
Adding an IPS sensor	40
Configuring IPS sensors	40
Configuring filters	42
Configuring pre-defined and custom overrides	43
DoS sensors	45
Viewing the DoS sensor list	46
Configuring DoS sensors	46
Understanding the anomalies	48
SYN flood attacks	51
What is a SYN flood attack?	51
How SYN floods work	51
The FortiGate IPS Response to SYN flood attacks	52
What is SYN threshold?	52
What is SYN proxy?	52
How IPS works to prevent SYN floods	52
Configuring SYN flood protection	54
Suggested settings for different network conditions	54
ICMP sweep attacks	55
What is an ICMP sweep?	55
How ICMP sweep attacks work	55
The FortiGate IPS response to ICMP sweep attacks	55
Predefined ICMP signatures	56
ICMP sweep anomalies	57
Configuring ICMP sweep protection	58
Suggested settings for different network conditions	58
Index	59

	FortiGate IPS User Guide Version 3.0 MR7
4	01-30007-0080-20080916

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Fortinet manual Protocol decoders, IPS sensors, DoS sensors, SYN flood attacks, Icmp sweep attacks, Index

Contents

E R G U I D E Trademarks Contents Protocol decoders IPS sensorsDoS sensors SYN flood attacks Introduction FortiGate IPS About this document Fortinet documentationDocument conventions Typographic conventions FortiGate Pptp VPN User Guide Fortinet Knowledge Center Customer service and technical supportComments on Fortinet technical documentation IPS settings and controls IPS overview and general configurationThis section contains the following topics When to use IPS Default signature and anomaly settingsDefault fail open setting Config ips global Set fail-open enable disable end Setting the buffer size Configuring logging and alert emailMonitoring the network and dealing with attacks Controlling sessions Attack log messages Signature Anomaly FortiGuard Center Using IPS sensors in a protection profile Creating a protection profile that uses IPS sensorsAdding protection profiles to firewall policies Select Create New Adding protection profiles to user groups Using IPS sensors in a protection profile IPS predefined signatures Predefined signaturesViewing the predefined signature list Settings EnableColumn Clear All Filters Create a sensor and add IPS filters to it Viewing the predefined signature list IPS custom signatures Custom signaturesViewing the custom signature list Custom signature configuration Adding custom signatures using the web-based managerAdding custom signatures using the CLI Command syntax pattern Custom signature fields Creating custom signaturesShows the valid characters for custom signature fields Custom signature syntax AttackidName BufferOverflow Srcport Content keywords Keyword and value Description Deprecated, see pattern and context keywords Pattern GET Context uriPattern yahoo.com Context host Pcre Regex/mdelimRegexdelimismxAEGRU Uri !uristr Protocol tcp IP header keywords Keyword and Value Description TCP header keywords Keyword and Value Description Tcpflags AP Tcpflags S,12 Icmp keywords Keyword and Value Usage UDP header keywords Keyword and Value DescriptionOther keywords Keyword and Value Description Example custom signatures Example 1 signature to block access to example.comSbid --name Block.example.com Sbid --name Block.example.com Sbid --name Block.SMTP.VRFY.CMD Example 2 signature to block the Smtp ‘vrfy’ commandSbid --name Block.SMTP.VRFY.CMD --pattern vrfy Creating custom signatures Protocol decoders Protocol decodersUpgrading the IPS protocol decoder list Viewing the protocol decoder list Protocol decoder list Protocols Protocol decoder names Port Alldefault AlldefaultpassIPS sensors Viewing the IPS sensor list Configuring IPS sensors Adding an IPS sensorProtectclient Protectemailserver IPS sensor attributes IPS sensor filters Configuring filters ResetIPS sensor overrides Delete and Edit Delete or edit the filter Icons Configuring pre-defined and custom overrides Application Exempt IP Source DoS sensors Configuring DoS sensors Viewing the DoS sensor listSequence in which the sensors examine network traffic Appears, and select OK Anomaly configuration DoS sensor attributesName Enter or change the DoS sensor name Comments Will appear in the DoS sensor list Understanding the anomalies Anomaly Description Tcpdstsession UdpfloodUdpscan Udpsrcsession Understanding the anomalies SYN flood attacks What is a SYN flood attack?How SYN floods work What is SYN threshold? What is SYN proxy?FortiGate IPS Response to SYN flood attacks How IPS works to prevent SYN floods IPS operation before synflood threshold is reached Suggested settings for different network conditions Configuring SYN flood protectionConfigure the options for tcpsynflood Select OK What is an Icmp sweep? Icmp sweep attacksHow Icmp sweep attacks work FortiGate IPS response to Icmp sweep attacks Predefined Icmp signatures Icmp sweep anomalies Configuring Icmp sweep protection Index FortiGate Version 3.0 MR7 IPS User Guide Technical support