Fortinet manual Network performance, When to use IPS, Default signature and anomaly settings

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Network performance

IPS overview and general configuration

To create an IPS sensor, go to Intrusion Protection > IPS Sensor. See “IPS sensors” on page 39 for details. To access the protection profile IPS sensor selection, go to Firewall > Protection Profile, select Edit or Create New, and select IPS.

To create a DoS Sensor, go to Intrusion Protection > DoS Sensor. See “DoS sensors” on page 45 for details.

When to use IPS

IPS is best for large networks or for networks protecting highly sensitive information. Using IPS effectively requires monitoring and analysis of the attack logs to determine the nature and threat level of an attack. An administrator can adjust the threshold levels to ensure a balance between performance and intrusion prevention. Small businesses and home offices without network administrators may be overrun with attack log messages and not have the networking background required to configure the thresholds and other IPS settings. In addition, the other protection features in the FortiGate unit, such as antivirus (including grayware), spam filters, and web filters offer excellent protection for all networks.

Network performance

The FortiGate IPS is extremely accurate and reliable as an in-line network device. Independent testing shows that the FortiGate IPS successfully detects and blocks attacks even under high traffic loads, while keeping latency within expected limits.

This section describes:

•Default signature and anomaly settings

•Default fail open setting

•Controlling sessions

•Setting the buffer size

Default signature and anomaly settings

You can use IPS sensors to apply appropriate IPS signatures to different protection profiles, then different firewall policies.

Default fail open setting

If for any reason the IPS should cease to function, it will fail open by default. This means that crucial network traffic will not be blocked and the Firewall will continue to operate while the problem is resolved.

Change the default fail open setting using the CLI:

config ips global

set fail-open [enable disable] end

	FortiGate IPS User Guide Version 3.0 MR7
10	01-30007-0080-20080916

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Contents E R G U I D E Trademarks Contents DoS sensors Protocol decodersIPS sensors SYN flood attacksIntroduction FortiGate IPSDocument conventions About this documentFortinet documentation Typographic conventionsFortiGate 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 Default fail open setting When to use IPSDefault signature and anomaly settings Config ips global Set fail-open enable disable endMonitoring the network and dealing with attacks Setting the buffer sizeConfiguring logging and alert email Controlling sessionsAttack log messages Signature Anomaly FortiGuard CenterAdding protection profiles to firewall policies Using IPS sensors in a protection profileCreating a protection profile that uses IPS sensors Select Create NewAdding protection profiles to user groups Using IPS sensors in a protection profile IPS predefined signatures Predefined signaturesViewing the predefined signature list Column SettingsEnable Clear All FiltersCreate a sensor and add IPS filters to it Viewing the predefined signature list IPS custom signatures Custom signaturesViewing the custom signature list Adding custom signatures using the CLI Custom signature configurationAdding custom signatures using the web-based manager Command syntax patternCustom signature fields Creating custom signaturesShows the valid characters for custom signature fields Name BufferOverflow Custom signature syntaxAttackid SrcportContent keywords Keyword and value Description Deprecated, see pattern and context keywords Pattern yahoo.com Pattern GETContext uri Context hostRegexdelimismxAEGRU PcreRegex/mdelim Uri !uristrProtocol tcp IP header keywords Keyword and Value DescriptionTCP header keywords Keyword and Value Description Tcpflags AP Tcpflags S,12Icmp 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 PortIPS sensors AlldefaultAlldefaultpass Viewing the IPS sensor listProtectclient Configuring IPS sensorsAdding an IPS sensor ProtectemailserverIPS sensor attributes IPS sensor filtersIPS sensor overrides Configuring filtersReset Delete and Edit Delete or edit the filter IconsConfiguring pre-defined and custom overrides ApplicationExempt IP SourceDoS sensors Sequence in which the sensors examine network traffic Configuring DoS sensorsViewing the DoS sensor list Appears, and select OKName Enter or change the DoS sensor name Comments Anomaly configurationDoS sensor attributes Will appear in the DoS sensor listUnderstanding the anomalies Udpscan Anomaly Description TcpdstsessionUdpflood UdpsrcsessionUnderstanding the anomalies SYN flood attacks What is a SYN flood attack?How SYN floods work FortiGate IPS Response to SYN flood attacks What is SYN threshold?What is SYN proxy? How IPS works to prevent SYN floodsIPS operation before synflood threshold is reached Suggested settings for different network conditions Configuring SYN flood protectionConfigure the options for tcpsynflood Select OK How Icmp sweep attacks work What is an Icmp sweep?Icmp sweep attacks 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