URL filter

The URL filter uses specific URLs with patterns containing text and regular expressions so the FortiGate can process the traffic based on the filter action (exempt, block, allow, monitor) and web pages that match the criteria. Once a URL filter is configured, it can be applied to a firewall policy.

The following filter types are available:

URL filter type	Description
Simple	The FortiGate tries to strictly match the full context. For example, if you enter www.facebook.com in the URL field, it only matches traffic with www.facebook.com. It won't match facebook.com or message.facebook.com. When the FortiGate finds a match, it performs the selected URL action.
Regular expression/ wildcard	The FortiGate tries to match the pattern based on the rules of regular expressions or wildcards. For example, if you enter *fa* in the URL field, it matches all the content that has fa such as www.facebook.com, message.facebook.com, fast.com, and so on. When the FortiGate finds a match, it performs the selected URL action.

For more information, see the URL Filter expressions technical tip in the Knowledge Base.

The following actions are available:

URL filter action	Description
Exempt	The traffic is allowed to bypass the remaining FortiGuard web filters, web content filters, web script filters, antivirus scanning, and DLP proxy operations.
Block	The FortiGate denies or blocks attempts to access any URL that matches the URL pattern. A replacement message is displayed.
Allow	The traffic is passed to the remaining FortiGuard web filters, web content filters, web script filters, antivirus proxy operations, and DLP proxy operations. If the URL does not appear in the URL list, the traffic is permitted.
Monitor	The traffic is processed the same way as the Allow action. For the Monitor action, a log message is generated each time a matching traffic pattern is established.

The exempt URL filter action can be configured to bypass all or certain security profile operations. This setting can only be configured in the CLI.

If the action is set to exempt, use set exempt to select the security profile operations that exempt URLs skip.

config webfilter urlfilter
    edit <id>
        config entries
            edit <id>
                set action exempt
                set exempt {av web-content activex-java-cookie dlp fortiguard range-block pass antiphish all}
            next
        end
    next
end

Option	Description
av	Antivirus scanning
web-content	Web filter content matching
activex-java-cookie	ActiveX, Java, and cookie filtering
dlp	DLP scanning
fortiguard	FortiGuard web filtering
range-block	Range block feature
pass	Pass single connection from all
antiphish	Antiphish credential checking
all	Exempt from all security profiles

These exempt options are not visible in the GUI. Setting the URL filter Action to Exempt will exempt URLs from all security profiles.

In the following example, a URL filter will be created to block the facebook.com URL using a wildcard.

Configuring a URL filter in the GUI

To create a URL filter for Facebook:

1. Go to Security Profiles > Web Filter and click Create New, or edit an existing profile.
2. In the Static URL Filter section, enable URL Filter.
3. Click Create New. The New URL Filter pane opens.
4. For URL, enter *facebook.com, for Type, select Wildcard, and for Action, select Block.

   

5. Click OK. The entry appears in the table.

   

6. Configure the other settings as needed.
7. Click OK.

To apply the web filter profile to a firewall policy:

1. Go to Policy & Objects > Firewall Policy.
2. Edit a policy, or create a new one.
3. In the Security Profiles section, enable Web Filter and select the profile you created.
4. Set SSL Inspection to certificate-inspection.

   

   The no-inspection profile does not perform SSL inspection, so it should not be selected with other UTM profiles.

5. Configure the other settings as needed.
6. Click OK.

Configuring a URL filter in the CLI

To create a URL filter for Facebook:

config webfilter urlfilter
    edit 1
        set name "webfilter"
        config entries
            edit 1
                set url "*facebook.com"
                set type wildcard
                set action block
            next
        end
    next
end

To apply the URL filter to a web filter profile:

config webfilter profile
    edit "webfilter" 
        config web
            set urlfilter-table 1
        end
        config ftgd-wf
            ...
        end
    next
end

To apply the web filter profile to a firewall policy:

config firewall policy
    edit 1
        set name "WF"
        set srcintf "wan2"
        set dstintf "wan1"
        set srcaddr "all"
        set dstaddr "all"
        set action accept
        set schedule "always"
        set service "ALL"
        set utm-status enable
        set inspection-mode proxy
        set logtraffic all
        set webfilter-profile "webfilter" 
        set ssl-ssh-profile "certificate-inspection"
        set nat enable
    next
end

Verifying the URL filter results

Verify the URL filter results by going to a blocked website. For example, when you go to the Facebook website, the replacement message appears:

To customize the URL web page blocked message:

1. Go to System > Replacement Messages.
2. In the HTTP section, select URL Block Page and click Edit.
3. Edit the HTML to customize the message.

   

To check web filter logs in the GUI:

1. Go to Log & Report > Security Events.
2. Click the Web Filter card name.
3. If there are a lot of log entries, click Add Filter and select Event Type > urlfilter to display logs generated by the URL filter.

   

To check web filter logs in the CLI:

# execute log filter category utm-webfilter			
# execute log display

1: date=2019-04-22 time=11:48:43 logid="0315012544" type="utm" subtype="webfilter" eventtype="urlfilter" level="warning" vd="vdom1" eventtime=1555958923322174610 urlfilteridx=0 urlsource="Local URLfilter Block" policyid=1 sessionid=649063 srcip=10.1.200.15 srcport=50472 srcintf="wan2" srcintfrole="wan" dstip=157.240.18.35 dstport=443 dstintf="wan1" dstintfrole="wan" proto=6 service="HTTPS" hostname="www.facebook.com" profile="webfilter" action="blocked" reqtype="direct" url="/" sentbyte=1171 rcvdbyte=141 direction="outgoing" msg="URL was blocked because it is in the URL filter list" crscore=30 craction=8 crlevel="high"