URL filter FAQ

Here you can find the answers to many frequently asked questions about ufdbGuard, the URL filter for Squid.  Feel free to contact the support desk if you have a question that is not answered here.

What is a URL database?
What are the requirements to use ufdbGuard?
Is ufdbGuard really free software?
Is Linux supported?
Is LDAP supported?
How does URLfilterDB work?
What is ufdbGuard?
What is Squid?
Can I use the URL database without ufdbGuard?
Can I use ufdbGuard without the database of URLfilterDB?
What web proxies can use ufdbGuard?
Can ufdbGuard replace squidGuard?
What web content can be blocked?
When is a site included in a blocked category?
What adult content can be blocked by URLfilterDB?
Does ufdbGuard block UltraSurf ?
Does ufdbGuard block Tor ?
Can I overrule categories?
Can I suggest a URL be added to or removed from the database ?
What is the difference between a URL filter and a content filter?
Why is the HTTPS protocol a security risk?
How can I configure ufdbGuard?
Does ufdbGuard consume much memory?
What is the ufdbGuard API?
What is "end of life" ?
I want to install ufdbGuard, but compiling the ufdbGuard code results in errors
How can I test URLfilterDB before buying?
How much does a subscription to URLfilterDB cost?
How can I make payments for a URLfilterDB subscription?

 

What is a URL database?
A URL database is used by URL filtering software to selectively block access to unwanted web content.
Back to top

 

What are the requirements to use ufdbGuard for Squid?
You need the following hardware and software to use ufdbGuard for Squid:
Hardware: The hardware requirements depend on the number of users.
Memory: 4-8 GB on 64-bit systems
Free disk space: 10 GB
CPU any CPU that runs Linux, FreeBSD or Solaris
CPU number and class:
ufdbGuard runs on the same server as where Squid runs.  ufdbGuard uses very little resources in comparison to Squid.  As a rule of thumb, reserve 15% of CPU resources for ufdbGuard.
Software:
Operating system: Linux, FreeBSD, or Solaris
Web server software: Apache
Web proxy: Squid
Internet filter software: ufdbGuard
Both the popular Squid web proxy and our ufdbGuard internet filter software are free!
Back to top

 

Is ufdbGuard really free software?
Yes.  ufdbGuard has always been free software with a GNU GPL2 license since its first release in 2005.
Also note that ufdbGuard can be used with any text-based URL database and/or with our commercial URL database.
Back to top

 

Is Linux supported?
Yes. ufdbGuard is developed on Linux (Ubuntu 22.04) and tested on on various platforms.
Back to top

 

Is LDAP supported?
Starting with version 1.30 LDAP support is easy to integrate due to the new configuration feature execuserlist which also supports Active Directory, Kerberos and any other queriable database with usernames.
Back to top

 

How does URLfilterDB work?
In most companies, web browsers like Internet Explorer use a web proxy to visit the Internet. The web proxy can be extended with an Internet filter to block the content of certain web pages. The ufdbGuard Internet filtering software uses the URLfilterDB database to decide which web content is filtered. For more information, we refer to the "How it works" page on this site.
Back to top

 

What is ufdbGuard?
ufdbGuard is the fastest internet filter that can be used with Squid. ufdbGuard is free and can be downloaded freely.
Back to top

 

What is Squid?
Squid is a popular and free web proxy. A web proxy sits in between a web browser like Internet explorer and the Internet. Squid and ufdbGuard integrate seamlessly.
Back to top

 

Can I use the URL database without ufdbGuard?
No. The URL database comes in a format suitable for ufdbGuard only.
Back to top

 

Can I use ufdbGuard without the database of URLfilterDB?
Yes. ufdbGuard comes with a program to generate a .ufdb file from a plain text file or URL blacklist.
Back to top

 

What web proxies can use ufdbGuard?
At this moment, Squid is the only proxy server that ufdbGuard supports.
Back to top

 

Can ufdbGuard replace squidGuard?
Absolutely! ufdbGuard is an excellent alternative for squidGuard because it is backed by a support desk, has regularly new features and bug fixes, and is 3 times faster.
Back to top

 

What web content can be blocked?
The URL database contains a set of website categories (also known as “blacklists”). The administrator can choose which URL categories are blocked for access, and which URL categories the users are allowed to visit.
URLfilterDB has the following categories :
  • Adult & sexually explicit, including obscene content
  • Advertisements
  • AI Chat
  • Alcohol
  • Alternative DNS
  • Arms
  • Audio & video
  • Alternative DNS
  • Chat
    subcategories: AIM, Ebuddy, Facebook, Google, ICQ, MSN, Skype, Whatsapp, Talkatone, Yahoo messenger
  • Dailymotion
  • Dating & Personals
  • DNS-over-HTTPS
  • Drugs
  • Education
  • Entertainment
  • External Applications
    subcategories: Citrix Online, iCloud, Telegram
  • Finance & Investment
  • Food
  • Forums
  • Gambling
  • Games
  • Hacking & Warez
  • Health
  • Housing
  • Job Search & Career Development
  • Malware   (also includes URLs from abuse.ch)
  • Microsoft Data Collection
  • News
  • Parked domain
  • Peer-to-peer (P2P)
  • Personal weblogs & private home pages
  • Questionable Movies (movies and series with questionable legal status)
  • Religion
  • Search Engine
  • Shops
  • Social Networks
    subcategories: Badoo, Facebook, Google+, Twitter
  • Soft Drugs
  • Sports
  • Toolbars
  • Safe sites
    subcategories: Google Safebrowsing, Microsoft Smartscreen
  • Travel
  • Violence/Offensive & Hate
  • Vimeo
  • Web Proxies, anonymizers and all filter circumvention sites
    subcategories: Teamviewer, Silk (Amazon), UCweb, Puffin Browser, Translators
  • Web Radio
  • Web TV, includes all sites with lots of videos, including Youtube
  • Web-based email
  • Youtube
  • Browser-specific: Mozilla, Chrome
The administrator can add any number of user-defined categories to whitelist and blacklist (parts of) sites.
Back to top

 

When is a site included in a blocked category?
A site is included when it contains one or more items that fit into a category. To prevent blocking too much, the database is built with a policy to include only subdomains of sites whenever possible. For example, if site1.com has a separate adult section in adult.site1.com, only this subdomain is included in the adult category. This means that www.site1.com is not in the adult category. On the other hand, if www.site2.com has a mix of adult and non-adult material that is not clearly divided into subdomains or subdirectories inside a domain, the whole domain is included in the adult category.
Back to top

 

What adult content can be blocked by URLfilterDB?
The adult category includes sites that contain hardcore and softcore porn, nudity, erotic stories, erotic art, fetishes, escorts, adult portals, lingerie and sites where one must be over 18 to enter. Any "non-adult" site that has an explicit adult advertisement is also included in the adult category!
Back to top

 

Does ufdbGuard block UltraSurf ?
Yes, UltraSurf is blocked when the options to verify SSL certificates for HTTPS connections and block HTTPS for URLs which have no fully qualified domain name (FQDN) are used.
Back to top

 

Does ufdbGuard block Tor ?
Yes, Tor is blocked when the options to verify SSL certificates for HTTPS connections and block HTTPS for URLs which have no fully qualified domain name (FQDN) are used.
Back to top

 

Can I overrule categories?
You can block a category as a whole, while still allowing access to one particular website in that category. Just include this website in the exception category "always allow"; this prevents blocking.
If you want to block access to a single website that is not in any category (e.g. www.fbi.gov), include this site in the category "always deny".
Both categories are maintained by the proxy administrator, and never by URLfilterDB!
Back to top

 

Can I suggest a URL be added to or removed from the database?
You can suggest any URL for inclusion or removal of the blacklist using our website.
Back to top

 

What is the difference between a URL filter and a content filter?
A URL filter uses a URL database with verified domains to block domains. A content filter guesses the nature of each page of each website "on the fly", by scanning the web pages for words like "sex".
A URL filter has several advantages over a content filter. For instance, a URL filter can block HTTPS traffic, while a content filter cannot because HTTPS is encrypted. Moreover, the risk of an incorrect classification is significantly higher with content filters. Also, CPU requirements for content filters are generally higher than for URL filtering solutions.
Back to top

 

Why is the HTTPS protocol a security risk?
HTTPS encrypts all data that is sent between a client and a web server.   This is useful for prohibiting eavesdropping on the data while it is transported over the Internet.  But it also enables setting up so-called “proxy tunnels” between a PC on a protected network and any system on the Internet.  Using a proxy tunnel, any system on the Internet can set up an unauthorized connection to a system on the protected network.  ufdbGuard offers the unique feature of dynamically detecting and blocking proxy tunnels.  A more detailed explanation is given in Why HTTPS is a security threat.
Back to top

 

How can I configure ufdbGuard?
ufdbGuard is extremely easy to configure. Once you have defined the blocking policy (e.g. which categories of sites to block), just enter this policy in the ufdbGuard configuration and you are ready to use it!
ufdbGuard is powerful and has many features and the support desk responds to all questions about the configuration within 1 business day.
Back to top

 

Does ufdbGuard consume much memory?"
The memory requirements are modest: 1.3 GB on 64-bit systems. 

 

What is the ufdbGuard API?
The ufdbGuard API is a library that can be used by 3rd party applications.  The ufdbGuard API provides a simple interface to the URL classification engine and hence gives system integrators and solution vendors access to a powerful API which performs extremely well.  Contact us to receive more information.

 

What is "end of life" ?
ufdbGuard is released two or three times per year. The support desk usually only supports the three most recent versions of ufdbGuard and may declare older versions of ufdbGuard "end of life".  The support desk of URLfilterDB does not support versions declared "end of life".

 

I want to install ufdbGuard, but compiling the ufdbGuard code results in errors
If you get errors during the compilation of the ufdbGuard sources, the most likely cause is that the OpenSSL or Bzlib header files cannot be found. In this case, install the packages libssl-devel and libbz2-devel from the Linux installation media.
Back to top

 

How can I test URLfilterDB before buying?
On this website you can register for a 60-day trial version of URLfilterDB to test it against URL filters and content filters. We are confident that you will find that URLfilterDB’s speed and accuracy of blocking much superior to its competitors.
Back to top

 

How much does a subscription to URLfilterDB cost?
Use the quote request form to ask for a subscription quote for your organization. Alternatively, use the ROI calculator to see how little time your ROI on URLfilterDB will be!
Back to top

 

How can I make payments for a URLfilterDB subscription?
We accept payments by international money transfer to our bank account in the Netherlands. The invoice contains all details to make a transfer. Customers in Euro countries will always be billed in Euro. Other customers may choose to be billed in EUR or USD.
Back to top