Fortiguard Dns Filter

[Curtis Boykins]

TheFortiGuard Web Filtering service includes over 45 million individual website ratings that apply to more than two billion pages. When the FortiGuard filter is enabled in a web filter and is applied to firewall policies, if a request for a web page appears in traffic controlled by one of the firewall policies, the URL is sent to the nearest FortiGuard server. The URL category or rating is returned. If the category is blocked, the FortiGate shows a replacement message in place of the requested page. If the category is not blocked, the page request is sent to the requested URL as normal.

The priority of categories is local category > external category > FortiGuard built-in category. If a URL is configured as a local category, it only follows the behavior of local category and not external or FortiGuard built-in category.

NSE4 trainee here. Just trying to understand the functional real world difference between Allow and Exempt in the Web Filter. I understand that Allow continues through the remainder of the security profiles such as AV, IPS, Fortiguard web filtering etc whereas Exempt passes any further security inspection.

What I don't understand is a situation where allow would actually do anything compared to exempt. In my experience, when a client requests for a URL to be whitelisted, the URL is already blocked by Fortiguard. When I select "Allow", it goes through normal "Web Filtering", which it passes due to the allow rule, but then is blocked by Fortiguard web filtering. When I select "Exempt", it passes through Fortiguard Web Filtering and any remaining security filters.

What is the use case for the "Allow" rule? When would the rule actually allow traffic? What else would be blocking the web traffic except for the Fortiguard web filter? Also, it's annoying that there's no inbetween - either bypass nothing or bypass Fortiguard web filter and every other security profile.

Allow: Traffic is oassed to remaining operations, includin FortiGuard web filter, web content filter, web scripts filters and av scanning.

Exempt: Allow traffic from tusted sources to BYPASS all security inspections

My question was relating to the allow rule's functionality. What is the use case for allow? When would "allow" actually allow something past the web filter without it then hitting the fortiguard web filter and being blocked?

The Fortinet Security Fabric brings together the concepts of convergence and consolidation to provide comprehensive cybersecurity protection for all users, devices, and applications and across all network edges.

Protect your organization by blocking access to malicious, hacked, or inappropriate websites with FortiGuard Web Filtering. Web filtering is the first line of defense against web-based attacks. Malicious or hacked websites, a primary vector for initiating attacks, trigger downloads of malware, spyware, or risky content.

FortiGuard URL Database Categories are based upon the Web content viewing suitability of three major groups of customers: enterprises, schools, and home/families. They also take into account customer requirements for Internet management. The categories are defined to be easily manageable and patterned to industry standards.

Get ExpressVPN NowImportant: You will have to use the ExpressVPN Chrome or FireFox extension (after you have created an account, you will be able to download the extensions from the site) to unblock FortiGuard web filter. FortiGuard will not allow you to install any VPN apps on your computer, but you can still add browser extensions.

Fortinet developed FortiGuard Web Filtering, a web filtering software used by schools and businesses to block access to various websites through a URL filter. It could be that school or business administrators want to filter out inappropriate, offensive, or illegal content; or prevent media streaming sites from using too much bandwidth and slowing down the network.

Any attempt to access a blocked site on a blocklist will result in the user receiving a message from FortiGuard indicating that access is blocked. Log files generated by the FortiGuard application record all access attempts.

Just request that the person is managing the FortiGuard Web Filtering tool grant access to the specific sites you need. Theoretically, this is the most straightforward technique; however, opening up the filtering such that dangerous websites are also made available may be impossible.

FortiGuard maintains a list of blocklisted websites, and every time you try to access those sites, it will prevent you from doing so in case FortiGuard is installed and enabled on your device or network.

This ExpressVPN chrome extension you are talking about is also paid and its not free to use and I also tried other VPNs their extensions also not working while this Fortinet is active. This has no solution as of now, Fortinet is complete blocking main entertainment and social media sites and has no option to disable it.

2. You may have to try out a few servers until you will find one that will not be blocked. Many VPN IP addresses will be blocked by FortiGuard but a lot will still work. You just need to keep trying until you find one that works.

Most critical of them is Web Filter rating query - if your Fortigate cannot get answer what category the web site belongs to, access to this web site will be blocked by default. It means that if for any reason Fortigate cannot reach Fortiguard servers and it has security rules with Web Filtering by Category configured - those rules will BLOCK users access to ANY website, not just malicious ones.

First, check status of license/subscription and FortiGuard connection status in System -> FortiGuard - the Web Filtering status should be in green. This checks subscription license status, but not always detects connection to the FortiGuard status. If you see it red, it is most probably a license/subscription issue to be checked with Fortinet TAC, as subscription checks are done once in a while and are cached. To check actual connectivity to the FortiGuard servers - on the same page, under Filtering subsection, there is Test Connectivity button to push. It should return status as Up/green. Also pay attention to the widget on the same page in the right bottom corner FortiGuard Filter Rating Servers, it shows real time stats and IP addresses of the servers the Fortigate is trying to reach. If timings are unusually high and in red, there could be network connectivity problem, we will look at next.

Even better check is to run ping exe ping to all the hostnames above to see if the Fortigate can resolve AND can reach them. The most important of them being service.fortiguard.net.

Here:

Status - shows if Web Filtering as a service is enabled.

Protocol - via what protocol this Fortigate is trying to reach FortiGuard servers (more on this below).

Anycast - whether this Fortigate is trying to reach Anycast servers of FortiGuard (more on this below).

Server List - actual list of FortiGuard servers that this Fortigate was/is trying to reach. Here most important is status legend:

- F: failed, bad - Fortigate tried few times to reach this server to no avail. Note that it is bad only if ALL servers in the list have this status. It is OK if only few of the servers are unreachable.

- D: this server was successfully resolved from FQDN to its IP address, but it does not indicate its reachability yet.

- I: server to which Fortigate tries to initiate connection, most frequently goes with D,it does not indicate if a server is working or not yet.

- T: server was found, it answered, and is now being "timed", i.e. its answer time/RTT is being measured.

- TZ: Time Zone, while not a status indicator, Fortigate tries and prefers servers with the least time zone difference in hope of geographic proximity. Therefore, it is quite important to set correctly the time zone for your Fortigate.

Fortigate communicates for its functions with just one server at a time - the one on top of the list. The rest of the servers are being constantly monitored and their RTT, and packet loss measured. If the top-list server fails, it will be replaced with the next best one and so on. We do not have capability to influence this server list manually.

So if all servers in the list have F(ailed), what do we do next?. This may mean either all Fortiguard servers at the Fortinet side are down (less likely), or that this Fortigate has the problem of reaching them at the network level.

Fortigate can use several ports to talk to Fortiguard servers (or Fortiguard Distribution Network as they call it) - 53, 8888, 443, the default being 8888. The port 53 is a well known DNS protocol/port, only that Fortigate uses proprietary UDP/53 obfuscated/encrypted protocol to query the servers, and for this reason some IPS/anti-DDoS/etc protections on the way from Fortigate to FortiGuard may mark such traffic as malicious and drop it. You can check if it is the case by going to System -> FortiGuard -> Filtering and change (if set so) from port 53 to port 8888. On newer FortiOS versions (6.4 and up) they moved this to CLI only: config sys fortiguard then set port 538888443. So, as first debug measure it is recommended to try all possible ports and see if status of connection to the FortiGuard servers changes. Note about protocol I mentioned before - in 6.4 and newer they added option to force the communication to FortiGuard servers to be a valid HTTPS traffic, which is most likely to pass the Internet successfully. For this you have to enable it (in addition to setting port to 443) via CLI: config sys fortiguard, then set protocol https end.

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