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# Custom TLDs

Challenge platforms often use local domains with custom TLDs to access machines that have a dynamic IP address. Eg. box.htb on HackTheBox or room.thm on TryHackMe.

Some custom TLDs are also used internally on corporate environment such as .local, .home, .lan, .corp, .intra or even the name of your company used as TLD.

The issue is that only those 4 are standard: .test, .localhost, .invalid, .example. So other private TLDs are considered non-standard (custom) and won't be recognized by web browsers. That's not very annoying since putting a full URL in you browser search bar will work. But when the protocol (eg. http://, https://, ftp://) is omitted, when you provide only the domain (eg. corpowiki.lan and not https://corpowiki.lan), you will end up querying on your default search engine instead of reaching that internal private domain. That is annoying.

To prevent this behavior and register your custom TLD as if it was a public standard TLD, you can tweak options on your web browser.

For Mozilla Firefox:

  1. Reach the advanced setting page: about:config
  2. Add a boolean key for your custom TLD: browser.fixup.domainsuffixwhitelist.<myTLD> eg. browser.fixup.domainsuffixwhitelist.htb

Unfortunately this feature doesn't (and will never) exist for Chromium / Google Chrome users. But there is a trick to define a pseudo search engine. Example with .htb.

  1. Go to chrome://settings/searchEngines
  2. Add a new search engine
  3. Fill the 3 fields as follow:
  • Search engine: HackTheBox
  • Keyword: htb
  • URL with %s in place of query: http://%s.htb

Then typing your keyword followed by a space followed by the domain will form the searched FQDN, eg. HTB + SPACE + noraj will search http://noraj.htb.

See also:

dns