Fortinet IPS manual Monitoring the network and dealing with attacks, Controlling sessions

Page 11


IPS overview and general configuration	Monitoring the network and dealing with attacks

Controlling sessions

Use this command to ignore sessions after a set amount of traffic has passed.

The default is 204800 bytes.

config ips global

set ignore-session-bytes <byte_integer> end

Setting the buffer size

Set the size of the IPS buffer. The size of the buffer is model-dependent.

config ips global

set socket-size <ips_buffer_size> end

Monitoring the network and dealing with attacks

After configuring IPS and enabling it in protection profiles, it is time to set up tracking and notification of attacks. Enabling logging and alert email to maintain user awareness of attacks on the network.

The next step is dealing with attacks if and when they occur. The FortiGuard Center at http://www.fortinet.com/FortiGuardCenter/ provides a comprehensive Attack Encyclopedia to help decide what actions to take to further protect the network.

This section describes:

•Configuring logging and alert email

•Attack log messages

•The FortiGuard Center

Configuring logging and alert email

Whenever the IPS detects or prevents an attack, it generates an attack log message that can be recorded or sent as an alert email.

The FortiGate unit categorizes attack log messages by signature or anomaly and includes the attack name in the log message. Enable logging and alert email for attack signatures and attack anomalies.

Note: Attack and intrusion attempts occur frequently on networks connected to the Internet. Reduce the number of log messages and alert email by disabling signatures for attacks that the system is not vulnerable to (for example, web attacks when not running a web server).

To configure logging and alert email for IPS events using the web-based manager

1Go to Log&Report > Log Config > Log Setting.

2Select and configure the settings for any logging locations to use.

3Select Apply.

4Go to Log&Report > Log Config > Alert Email.

FortiGate IPS User Guide Version 3.0 MR7
01-30007-0080-20080916	11

Image 11

Contents E R G U I D E Trademarks Contents SYN flood attacks Protocol decodersIPS sensors DoS sensorsFortiGate IPS IntroductionTypographic conventions About this documentFortinet documentation Document 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 Config ips global Set fail-open enable disable end When to use IPSDefault signature and anomaly settings Default fail open settingControlling sessions Setting the buffer sizeConfiguring logging and alert email Monitoring the network and dealing with attacksAttack log messages Signature FortiGuard Center AnomalySelect Create New Using IPS sensors in a protection profileCreating a protection profile that uses IPS sensors Adding protection profiles to firewall policiesAdding protection profiles to user groups Using IPS sensors in a protection profile Viewing the predefined signature list Predefined signaturesIPS predefined signatures Clear All Filters SettingsEnable ColumnCreate a sensor and add IPS filters to it Viewing the predefined signature list Viewing the custom signature list Custom signaturesIPS custom signatures Command syntax pattern Custom signature configurationAdding custom signatures using the web-based manager Adding custom signatures using the CLIShows the valid characters for custom signature fields Creating custom signaturesCustom signature fields Srcport Custom signature syntaxAttackid Name BufferOverflowContent keywords Keyword and value Description Deprecated, see pattern and context keywords Context host Pattern GETContext uri Pattern yahoo.comUri !uristr PcreRegex/mdelim RegexdelimismxAEGRUIP header keywords Keyword and Value Description Protocol tcpTCP header keywords Keyword and Value Description Tcpflags S,12 Tcpflags APOther 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 Protocol decoder list Protocols Protocol decoder names Port Viewing the protocol decoder listViewing the IPS sensor list AlldefaultAlldefaultpass IPS sensorsProtectemailserver Configuring IPS sensorsAdding an IPS sensor ProtectclientIPS sensor filters IPS sensor attributesDelete and Edit Delete or edit the filter Icons Configuring filtersReset IPS sensor overridesApplication Configuring pre-defined and custom overridesSource Exempt IPDoS sensors Appears, and select OK Configuring DoS sensorsViewing the DoS sensor list Sequence in which the sensors examine network trafficWill appear in the DoS sensor list Anomaly configurationDoS sensor attributes Name Enter or change the DoS sensor name CommentsUnderstanding the anomalies Udpsrcsession Anomaly Description TcpdstsessionUdpflood UdpscanUnderstanding the anomalies How SYN floods work What is a SYN flood attack?SYN flood attacks How IPS works to prevent SYN floods What is SYN threshold?What is SYN proxy? FortiGate IPS Response to SYN flood attacksIPS operation before synflood threshold is reached Configure the options for tcpsynflood Select OK Configuring SYN flood protectionSuggested settings for different network conditions FortiGate IPS response to Icmp sweep attacks What is an Icmp sweep?Icmp sweep attacks How Icmp sweep attacks workPredefined Icmp signatures Icmp sweep anomalies Configuring Icmp sweep protection FortiGate Version 3.0 MR7 IPS User Guide IndexTechnical support