Fortinet Document Library

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Cookbook

6.2.0
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Local domain filter

In addition to FortiGuard's category-based domain filter, you can also can define your own local static domain filter to allow or block specific domains.

To configure DNS local domain filter on GUI:
  1. Go to Security Profiles > DNS Filter and edit or create a DNS Filter.
  2. In the Static Domain Filter section, enable Domain Filter.
  3. Click Create New to create your local domain filter entries.

To configure DNS local domain filter on CLI:
config dnsfilter domain-filter
    edit 1
        set name "demo"
        set comment ''
        config entries
            edit 1
                set domain "www.fortinet.com"
                set type simple
                set action allow
                set status enable
            next
            edit 2
                set domain "*.example.com"
                set type wildcard
                set action block
                set status enable
            next
            edit 3
                set domain "google"
                set type regex
                set action monitor
                set status enable
            next
        end
    next
end
Note

Wildcard entries are converted to regular expressions by FortiOS. As a result of this conversion, wildcards will match any suffix, as long as there is a word boundary following the search term.

For example:

config entries
    edit 1
        set domain "*.host"
        set type wildcard
    next
end

will match wp36.host and wp36.host.pressdns.com, but not wp36.host123.pressdnds.com.

To avoid this, use an explicit regular expression search string:

config entries
    edit 1
        set domain "^.*\\.host$"
        set type regexp
    next
end
To check the DNS local domain filter log in the GUI:
  1. Go to Log & Report > DNS Query to view the DNS query log.

    Since the local domain list "google" action is Monitor, it's blocked by FortiGuard category-based domain filter.

To check the DNS local domain filter log in the CLI:
7: date=2019-04-05 time=15:37:06 logid="1501054803" type="utm" subtype="dns" eventtype="dns-response" level="warning" vd="vdom1" eventtime=1554503826 policyid=1 sessionid=69132 srcip=10.1.100.18 srcport=49832 srcintf="port10" srcintfrole="undefined" dstip=172.16.95.16 dstport=53 dstintf="port9" dstintfrole="undefined" proto=17 profile="demo" xid=4612 qname="www.google.com" qtype="A" qtypeval=1 qclass="IN" ipaddr="208.91.112.55" msg="Domain belongs to a denied category in policy" action="redirect" cat=41 catdesc="Search Engines and Portals"

8: date=2019-04-05 time=15:37:06 logid="1500054000" type="utm" subtype="dns" eventtype="dns-query" level="information" vd="vdom1" eventtime=1554503826 policyid=1 sessionid=69132 srcip=10.1.100.18 srcport=49832 srcintf="port10" srcintfrole="undefined" dstip=172.16.95.16 dstport=53 dstintf="port9" dstintfrole="undefined" proto=17 profile="demo" xid=4612 qname="www.google.com" qtype="A" qtypeval=1 qclass="IN"

9: date=2019-04-05 time=15:36:59 logid="1501054400" type="utm" subtype="dns" eventtype="dns-response" level="warning" vd="vdom1" eventtime=1554503818 policyid=1 sessionid=69121 srcip=10.1.100.18 srcport=40659 srcintf="port10" srcintfrole="undefined" dstip=172.16.95.16 dstport=53 dstintf="port9" dstintfrole="undefined" proto=17 profile="demo" xid=24730 qname="www.example.com" qtype="A" qtypeval=1 qclass="IN" msg="Domain was blocked because it is in the domain-filter list" action="redirect" domainfilteridx=1 domainfilterlist="demo"

10: date=2019-04-05 time=15:36:59 logid="1500054000" type="utm" subtype="dns" eventtype="dns-query" level="information" vd="vdom1" eventtime=1554503818 policyid=1 sessionid=69121 srcip=10.1.100.18 srcport=40659 srcintf="port10" srcintfrole="undefined" dstip=172.16.95.16 dstport=53 dstintf="port9" dstintfrole="undefined" proto=17 profile="demo" xid=24730 qname="www.example.com" qtype="A" qtypeval=1 qclass="IN"

11: date=2019-04-05 time=15:36:51 logid="1501054401" type="utm" subtype="dns" eventtype="dns-response" level="information" vd="vdom1" eventtime=1554503810 policyid=1 sessionid=69118 srcip=10.1.100.18 srcport=33461 srcintf="port10" srcintfrole="undefined" dstip=172.16.95.16 dstport=53 dstintf="port9" dstintfrole="undefined" proto=17 profile="demo" xid=53801 qname="www.fortinet.com" qtype="A" qtypeval=1 qclass="IN" ipaddr="13.56.55.78, 54.183.57.55" msg="Domain was allowed because it is in the domain-filter list" action="pass" domainfilteridx=1 domainfilterlist="demo"

12: date=2019-04-05 time=15:36:51 logid="1500054000" type="utm" subtype="dns" eventtype="dns-query" level="information" vd="vdom1" eventtime=1554503810 policyid=1 sessionid=69118 srcip=10.1.100.18 srcport=33461 srcintf="port10" srcintfrole="undefined" dstip=172.16.95.16 dstport=53 dstintf="port9" dstintfrole="undefined" proto=17 profile="demo" xid=53801 qname="www.fortinet.com" qtype="A" qtypeval=1 qclass="IN"

Sequence and priority

In DNS Filter, local domain filter has a higher priority than FortiGuard category-based domain filter.

A DNS query is scanned and matched with local domain filter first. If an entry matches and the local filter entry's action is block, then that DNS query is blocked or redirected.

If local domain filter list has no match, then the FortiGuard category-based domain filter is used. If a DNS query domain name rating belongs to the block category, this query is blocked or redirected. If the FortiGuard category-based filter has no match, then the original resolved IP address is returned to the client DNS resolver.

The local domain filter action can be Block, Allow, or Monitor. If the local domain filter action is Allow and an entry matches, it will skip the FortiGuard category-based domain filter and directly return to client DNS resolver. If the local domain filter action is Monitor and an entry matches, it will go to FortiGuard category-based domain filter scanning and matching.

Local domain filter

In addition to FortiGuard's category-based domain filter, you can also can define your own local static domain filter to allow or block specific domains.

To configure DNS local domain filter on GUI:
  1. Go to Security Profiles > DNS Filter and edit or create a DNS Filter.
  2. In the Static Domain Filter section, enable Domain Filter.
  3. Click Create New to create your local domain filter entries.

To configure DNS local domain filter on CLI:
config dnsfilter domain-filter
    edit 1
        set name "demo"
        set comment ''
        config entries
            edit 1
                set domain "www.fortinet.com"
                set type simple
                set action allow
                set status enable
            next
            edit 2
                set domain "*.example.com"
                set type wildcard
                set action block
                set status enable
            next
            edit 3
                set domain "google"
                set type regex
                set action monitor
                set status enable
            next
        end
    next
end
Note

Wildcard entries are converted to regular expressions by FortiOS. As a result of this conversion, wildcards will match any suffix, as long as there is a word boundary following the search term.

For example:

config entries
    edit 1
        set domain "*.host"
        set type wildcard
    next
end

will match wp36.host and wp36.host.pressdns.com, but not wp36.host123.pressdnds.com.

To avoid this, use an explicit regular expression search string:

config entries
    edit 1
        set domain "^.*\\.host$"
        set type regexp
    next
end
To check the DNS local domain filter log in the GUI:
  1. Go to Log & Report > DNS Query to view the DNS query log.

    Since the local domain list "google" action is Monitor, it's blocked by FortiGuard category-based domain filter.

To check the DNS local domain filter log in the CLI:
7: date=2019-04-05 time=15:37:06 logid="1501054803" type="utm" subtype="dns" eventtype="dns-response" level="warning" vd="vdom1" eventtime=1554503826 policyid=1 sessionid=69132 srcip=10.1.100.18 srcport=49832 srcintf="port10" srcintfrole="undefined" dstip=172.16.95.16 dstport=53 dstintf="port9" dstintfrole="undefined" proto=17 profile="demo" xid=4612 qname="www.google.com" qtype="A" qtypeval=1 qclass="IN" ipaddr="208.91.112.55" msg="Domain belongs to a denied category in policy" action="redirect" cat=41 catdesc="Search Engines and Portals"

8: date=2019-04-05 time=15:37:06 logid="1500054000" type="utm" subtype="dns" eventtype="dns-query" level="information" vd="vdom1" eventtime=1554503826 policyid=1 sessionid=69132 srcip=10.1.100.18 srcport=49832 srcintf="port10" srcintfrole="undefined" dstip=172.16.95.16 dstport=53 dstintf="port9" dstintfrole="undefined" proto=17 profile="demo" xid=4612 qname="www.google.com" qtype="A" qtypeval=1 qclass="IN"

9: date=2019-04-05 time=15:36:59 logid="1501054400" type="utm" subtype="dns" eventtype="dns-response" level="warning" vd="vdom1" eventtime=1554503818 policyid=1 sessionid=69121 srcip=10.1.100.18 srcport=40659 srcintf="port10" srcintfrole="undefined" dstip=172.16.95.16 dstport=53 dstintf="port9" dstintfrole="undefined" proto=17 profile="demo" xid=24730 qname="www.example.com" qtype="A" qtypeval=1 qclass="IN" msg="Domain was blocked because it is in the domain-filter list" action="redirect" domainfilteridx=1 domainfilterlist="demo"

10: date=2019-04-05 time=15:36:59 logid="1500054000" type="utm" subtype="dns" eventtype="dns-query" level="information" vd="vdom1" eventtime=1554503818 policyid=1 sessionid=69121 srcip=10.1.100.18 srcport=40659 srcintf="port10" srcintfrole="undefined" dstip=172.16.95.16 dstport=53 dstintf="port9" dstintfrole="undefined" proto=17 profile="demo" xid=24730 qname="www.example.com" qtype="A" qtypeval=1 qclass="IN"

11: date=2019-04-05 time=15:36:51 logid="1501054401" type="utm" subtype="dns" eventtype="dns-response" level="information" vd="vdom1" eventtime=1554503810 policyid=1 sessionid=69118 srcip=10.1.100.18 srcport=33461 srcintf="port10" srcintfrole="undefined" dstip=172.16.95.16 dstport=53 dstintf="port9" dstintfrole="undefined" proto=17 profile="demo" xid=53801 qname="www.fortinet.com" qtype="A" qtypeval=1 qclass="IN" ipaddr="13.56.55.78, 54.183.57.55" msg="Domain was allowed because it is in the domain-filter list" action="pass" domainfilteridx=1 domainfilterlist="demo"

12: date=2019-04-05 time=15:36:51 logid="1500054000" type="utm" subtype="dns" eventtype="dns-query" level="information" vd="vdom1" eventtime=1554503810 policyid=1 sessionid=69118 srcip=10.1.100.18 srcport=33461 srcintf="port10" srcintfrole="undefined" dstip=172.16.95.16 dstport=53 dstintf="port9" dstintfrole="undefined" proto=17 profile="demo" xid=53801 qname="www.fortinet.com" qtype="A" qtypeval=1 qclass="IN"

Sequence and priority

In DNS Filter, local domain filter has a higher priority than FortiGuard category-based domain filter.

A DNS query is scanned and matched with local domain filter first. If an entry matches and the local filter entry's action is block, then that DNS query is blocked or redirected.

If local domain filter list has no match, then the FortiGuard category-based domain filter is used. If a DNS query domain name rating belongs to the block category, this query is blocked or redirected. If the FortiGuard category-based filter has no match, then the original resolved IP address is returned to the client DNS resolver.

The local domain filter action can be Block, Allow, or Monitor. If the local domain filter action is Allow and an entry matches, it will skip the FortiGuard category-based domain filter and directly return to client DNS resolver. If the local domain filter action is Monitor and an entry matches, it will go to FortiGuard category-based domain filter scanning and matching.