Detecting attacks

Network Intrusion Detection System (NIDS)

 

 

Figure 67: Example signature group members list

Disabling NIDS attack signatures

By default, all NIDS attack signatures are enabled. You can use the NIDS signature list to disable detection of some attacks. Disabling unnecessary NIDS attack signatures can improve system performance and reduce the number of IDS log messages and alert emails that the NIDS generates. For example, the NIDS detects a large number of web server attacks. If you do not provide access to a web server behind your firewall, you might want to disable all web server attack signatures.

Note: To save your NIDS attack signature settings, Fortinet recommends that you back up your FortiGate configuration before you update the firmware and restore the saved configuration after the update.

To disable NIDS attack signatures

1Go to NIDS > Detection > Signature List.

2Scroll through the signature list to find the signature group that you want to disable.

Attack ID numbers and rule names in attack log messages and alert email match those in the signature group members list. You can scroll through a signature group members list to locate specific attack signatures by ID number and name.

3Clear the Enable check box.

4Select OK.

5Repeat steps 2 to 4 for each NIDS attack signature group that you want to disable.

Select Check All to enable all NIDS attack signature groups in the signature list.

Select Uncheck All to disable all NIDS attack signature groups in the signature list.

Adding user-defined signatures

You can create a user-defined signature list in a text file and upload it from the management computer to the FortiGate unit.

Note: You cannot upload individual signatures. You must include, in a single text file, all the user-defined signatures that you want to upload. The file can contain one or more signatures.

For information about how to write user-defined signatures, see the FortiGate NIDS

Guide.

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