FortiOS features available for logging – FortiOS 6

FortiOS features available for logging

Logs record FortiGate activity, providing detailed information about what is happening on your network. This recorded activity is found in log files, which are stored on a log device. However, logging FortiGate activity requires configuring certain settings so that the FortiGate unit can record the activity. These settings are often referred to as log settings, and are found in most security profiles, but also in Log & Report > Log Settings.

Log settings provide the information that the FortiGate unit needs so that it knows what activities to record. This topic explains what activity each log file records, as well as additional information about the log file, which will help you determine what FortiGate activity the FortiGate unit should record.


Traffic logs record the traffic that is flowing through your FortiGate unit. Since traffic needs firewall policies to properly flow through the unit, this type of logging is also referred to as firewall policy logging. Firewall policies control all traffic that attempts to pass through the FortiGate unit, between FortiGate interfaces, zones and VLAN sub-interfaces.

Logging traffic works in the following way:

l firewall policy has logging enabled on it (Log Allowed Traffic) l packet comes into an inbound interface l a possible log packet is sent regarding a match in the firewall policy, such as a URL filter l traffic log packet is sent, per firewall policy l packet passes and is sent out an interface

Traffic log messages are stored in the traffic log file. Traffic logs can be stored any log device, even system memory.

All security profile-related logs are now tracked within the Traffic logs, as of FortiOS 5.0, so all forward traffic can be searched in one place, such as if you are looking to see all activity from a particular address, security feature or traffic. Security profile logs are still tracked separately in the Security Log section, which only appears when logs exist.

If you have enabled and configured WAN Optimization, you can enable logging of this activity in the CLI using the config wanopt setting command. These logs contain information about WAN Optimization activity and are found in the traffic log file. When configuring logging of this activity, you must also enable logging within the security policy itself, so that the activity is properly recorded.


The Sniffer log records all traffic that passes through a particular interface that has been configured to act as a One-Armed Sniffer, so it can be examined separately from the rest of the Traffic logs.

FortiOS features available for logging

Other traffic

The traffic log also records interface traffic logging, which is referred to as Other Traffic. Other Traffic is enabled only in the CLI. When enabled, the FortiGate unit records traffic activity on interfaces as well as firewall policies. Logging Other Traffic puts a significant system load on the FortiGate unit and should be used only when necessary.

Logging other traffic works in the following way:

  • firewall policy has logging enabled on it (Log Allowed Traffic) and other-traffic l packet comes into an interface l interface log packet is sent to the traffic log that is enabled on that particular interface l possible log packet is sent regarding a match in the firewall policy, such as URL filter l interface log packet is sent to the traffic log if enabled on that particular interface l packet passes and is sent out an interface
  • interface log packet is sent to traffic (if enabled) on that particular interface


The event log records administration management as well as FortiGate system activity, such as when a configuration has changed, admin login, or high availability (HA) events occur. Event logs are an important log file to record because they record FortiGate system activity, which provides valuable information about how your FortiGate unit is performing.

Event logs help you in the following ways:

l keeping track of configuration setting changes l IPsec negotiation, SSL VPN and tunnel activity l quarantine events, such as banned users l system performance l HA events and alerts l firewall authentication events l wireless events on models with WiFi capabilities l activities concerning modem and internet protocols L2TP, PPP and PPPoE l VIP activities l AMC disk’s bypass mode l VoIP activities that include SIP and SCCP protocols.

As of 5.4, every ‘execute’ CLI command now generates an ‘audit’ event log, allowing you to track configuration changes. You can enable/disable this feature in the CLI:

config system global set cli-audit-log [enable|disable]


The FortiGate unit records event logs only when events are enabled.

Traffic shaping

Traffic shaping, per-IP traffic shaping and reverse direction traffic shaping settings can be applied to a firewall policy, appearing within the traffic log messages.

By enabling this feature, you can see what traffic shaping, per-IP traffic shaping and reverse direction traffic shaping settings are being used.

Data Leak Prevention

Data Leak Prevention logs, or DLP logs, provide valuable information about the sensitive data trying to get through to your network as well as any unwanted data trying to get into your network. The DLP rules within a DLP sensor can log the following traffic types:

l email (SMTP, POP3 or IMAP; if SSL content SMTPS, POP3S, and IMAPS) l HTTP l HTTPS l FTP l NNTP l IM

A DLP sensor must have log settings enabled for each DLP rule and compound rule, as well as applied to a firewall policy so that the FortiGate unit records this type of activity. A DLP sensor can also contain archiving options, which these logs are then archived to the log device.

NAC Quarantine

Within the DLP sensor, there is an option for enabling NAC Quarantine. The NAC Quarantine option allows the FortiGate unit to record details of DLP operation that involve the ban and quarantine actions, and sends these to the event log file. The NAC Quarantine option must also be enabled within the Event Log settings. When enabling NAC quarantine within a DLP Sensor, you must enable this in the CLI because it is a CLI-only command.

Media Access Control (MAC) address

MAC address logs provide information about MAC addresses that the FortiGate unit sees on the network as well as those removed from the network. These log messages are stored in the event log (as subtype network; you can view these log messages in Log & Report > System Events) and are, by default, disabled in the CLI. You can enable logging MAC addresses using the following command syntax:

config log setting set neighbor-event enable


When enabled, a new log message is recorded every time a MAC address entry is added to the ARP table, and also when a MAC address is removed as well. A MAC address log message is also recorded when MAC addresses are connected to the local switch, or from a FortiAP or FortiSwitch unit.

FortiOS features available for logging

Application control

Application control logs provide detailed information about the traffic that internet applications such as Skype are generating. The application control feature controls the flow of traffic from a specific application, and the FortiGate unit examines this traffic for signatures that the application generates.

The log messages that are recorded provide information such as the type of application being used (such as P2P software), and what type of action the FortiGate unit took. These log messages can also help you to determine the top ten applications that are being used on your network. This feature is called application control monitoring and you can view the information from a widget on the Executive Summary page.

The application control list that is used must have logging enabled within the list, as well as logging enabled within each application entry. Each application entry can also have packet logging enabled. Packet logging for application control records the packet when an application type is identified, similar to IPS packet logging.

Logging of application control activity can only be recorded when an application control list is applied to a firewall policy, regardless of whether or not logging is enabled within the application control list.


Antivirus logs are recorded when, during the antivirus scanning process, the FortiGate unit finds a match within the antivirus profile, which includes the presence of a virus or grayware signature. Antivirus logs provide a way to understand what viruses are trying to get in, as well as additional information about the virus itself, without having to go to the FortiGuard Center and do a search for the detected virus. The link is provided within the log message itself.

These logs provide valuable information such as:

  • the name of the detected virus l the name of the oversized file or infected file l the action the FortiGate unit took, for example, a file was blocked
  • URL link to the FortiGuard Center which gives detailed information about the virus itself

The antivirus profile must have log settings enabled within it so that the FortiGate unit can record this activity, as well as having the antivirus profile applied to a firewall policy.

Web filter

Web filter logs record HTTP traffic activity. These log messages provide valuable and detailed information about this particular traffic activity on your network. Web filtering activity is important to log because it can inform you about:

l what types of web sites employees are accessing l users attempting to access banned web sites and how often this occurs l network congestion due to employees accessing the Internet at the same time l web-based threats resulting from users visiting non-business-related web sites

Web Filter logs are an effective tool to help you determine if you need to update your web filtering settings within a web filter profile due to unforeseen threats or network congestion. These logs also inform you about web filtering quotas that have been configured for filtering HTTP traffic.

You must configure logging settings within the web filter profile and apply the filter to a firewall policy so that the FortiGate unit can record the activity.

IPS (attack)

IPS logs, also referred to as attack logs, record attacks that occurred against your network. Attack logs contain detailed information about whether the FortiGate unit protected the network using anomaly-based defense settings or signature-based defense settings, as well as what the attack was.

The IPS or attack log file is especially useful because the log messages that are recorded contain a link to the FortiGuard Center, where you can find more information about the attack. This is similar to antivirus logs, where a link to the FortiGuard Center is provided as well that informs you of the virus that was detected by the FortiGate unit.

An IPS sensor with log settings enabled must be applied to a firewall policy so that the FortiGate unit can record the activity.

Packet logs

When you enable packet logging within an IPS signature override or filter, the FortiGate unit examines network packets, and if a match is found, saves them to the attack log. Packet logging is designed to be used as a diagnostic tool that can focus on a narrow scope of diagnostics, rather than a log that informs you of what is occurring on your network.

You should use caution when enabling packet logging, especially within IPS filters. Filter configuration that contains thousands of signatures could potentially cause a flood of saved packets, which would take up a lot of storage space on the log device. It would also take a great deal of time to sort through all the log messages, as well as consume considerable system resources to process.

You can archive packets, but you must enable this option on the Log Settings page. If your log configuration includes multiple FortiAnalyzer units, packet logs are only sent to the primary (first) FortiAnalyzer unit. Sending packet logs to the other FortiAnalyzer units is not supported.

Email filter

Email filter logs, also referred to as spam filter logs, record information regarding the content within email messages. For example, within an email filter profile, a match is found that finds the email message to be considered spam.

Email filter logs are recorded when the FortiGate unit finds a match within the email filter profile and logging settings are enabled within the profile.

If you are using a Banned Words List for email filtering, note that the filter pattern number is only recorded when the source email address contains a banned word.

Archives (DLP)

Recording DLP logs for network use is called DLP archiving. The DLP engine examines email, FTP, IM, NNTP, and web traffic. Archived logs are usually saved for historical use and can be accessed at any time. IPS packet logs can also be archived, within the Log Settings page.


You can start with the two default DLP sensors that have been configured specifically for archiving log data, Content_Archive and Content_Summary. They are available in Security Profiles > Data Leak Prevention. Content_Archive provides full content archiving, while Content_Summary provides summary archiving. For more information about how to configure DLP sensors, see the Security Features chapter of the FortiOS Handbook.

You must enable the archiving to record log archives. Logs are not archived unless enabled, regardless of whether or not the DLP sensor for archiving is applied to the firewall policy.

Network scan

Network scan logs are recorded when a scheduled scan of the network occurs. These log messages provide detailed information about the network’s vulnerabilities regarding software, as well as the discovery of any further vulnerabilities.

A scheduled scan must be configured and logging enabled within the Event Log settings, for the FortiGate unit to record these log messages.

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This entry was posted in Administration Guides, Fortinet, FortiOS 6 on by .

About Mike

Michael Pruett, CISSP has a wide range of cyber-security and network engineering expertise. The plethora of vendors that resell hardware but have zero engineering knowledge resulting in the wrong hardware or configuration being deployed is a major pet peeve of Michael's. This site was started in an effort to spread information while providing the option of quality consulting services at a much lower price than Fortinet Professional Services. Owns PacketLlama.Com (Fortinet Hardware Sales) and Office Of The CISO, LLC (Cybersecurity consulting firm).

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