Anomaly Description Tcpdstsession, Udpflood, Udpscan | Fortinet IPS


DoS sensors	Understanding the anomalies

Anomaly	Description

tcp_dst_session	If the number of concurrent TCP connections to one destination IP
	address exceeds the configured threshold value, the action is
	executed.

udp_flood	If the UDP traffic to one destination IP address exceeds the
	configured threshold value, the action is executed. The threshold is
	expressed in packets per second.

udp_scan	If the number of UDP sessions originating from one source IP
	address exceeds the configured threshold value, the action is
	executed. The threshold is expressed in packets per second.

udp_src_session	If the number of concurrent UDP connections from one source IP
	address exceeds the configured threshold value, the action is
	executed.

udp_dst_session	If the number of concurrent UDP connections to one destination IP
	address exceeds the configured threshold value, the action is
	executed.

icmp_flood	If the number of ICMP packets sent to one destination IP address
	exceeds the configured threshold value, the action is executed.
	The threshold is expressed in packets per second.

icmp_sweep	If the number of ICMP packets originating from one source IP
	address exceeds the configured threshold value, the action is
	executed. The threshold is expressed in packets per second.

icmp_src_session	If the number of concurrent ICMP connections from one source IP
	address exceeds the configured threshold value, the action is
	executed.

icmp_dst_session	If the number of concurrent ICMP connections to one destination
	IP address exceeds the configured threshold value, the action is
	executed.

FortiGate IPS User Guide Version 3.0 MR7
01-30007-0080-20080916	49

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Fortinet IPS Anomaly Description Tcpdstsession, Udpflood, Udpscan, Udpsrcsession, Udpdstsession, Icmpflood, Icmpsweep

Contents

E R G U I D E Trademarks Contents IPS sensors Protocol decodersDoS sensors SYN flood attacks FortiGate IPS Introduction Fortinet documentation About this documentDocument 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 Default signature and anomaly settings When to use IPSDefault fail open setting Config ips global Set fail-open enable disable end Configuring logging and alert email Setting the buffer sizeMonitoring the network and dealing with attacks Controlling sessions Attack log messages Signature FortiGuard Center Anomaly Creating a protection profile that uses IPS sensors Using IPS sensors in a protection profileAdding 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 Enable SettingsColumn 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 Adding custom signatures using the web-based manager Custom signature configurationAdding custom signatures using the CLI Command syntax pattern Custom signature fields Creating custom signaturesShows the valid characters for custom signature fields Attackid Custom signature syntaxName BufferOverflow Srcport Content keywords Keyword and value Description Deprecated, see pattern and context keywords Context uri Pattern GETPattern yahoo.com Context host Regex/mdelim PcreRegexdelimismxAEGRU Uri !uristr IP header keywords Keyword and Value Description Protocol tcp TCP header keywords Keyword and Value Description Tcpflags S,12 Tcpflags AP 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 Protocol decoder list Protocols Protocol decoder names Port Viewing the protocol decoder list Alldefaultpass AlldefaultIPS sensors Viewing the IPS sensor list Adding an IPS sensor Configuring IPS sensorsProtectclient Protectemailserver IPS sensor filters IPS sensor attributes Reset Configuring filtersIPS sensor overrides Delete and Edit Delete or edit the filter Icons Application Configuring pre-defined and custom overrides Source Exempt IP DoS sensors Viewing the DoS sensor list Configuring DoS sensorsSequence in which the sensors examine network traffic Appears, and select OK DoS sensor attributes Anomaly configurationName Enter or change the DoS sensor name Comments Will appear in the DoS sensor list Understanding the anomalies Udpflood Anomaly Description TcpdstsessionUdpscan Udpsrcsession Understanding the anomalies SYN flood attacks What is a SYN flood attack?How SYN floods work What is SYN proxy? What is SYN threshold?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 Icmp sweep attacks What is an Icmp sweep?How Icmp sweep attacks work FortiGate IPS response to Icmp sweep attacks Predefined Icmp signatures Icmp sweep anomalies Configuring Icmp sweep protection FortiGate Version 3.0 MR7 IPS User Guide Index Technical support