=Captive portal checks= Firefox's [https://en.wikipedia.org/wiki/Captive_portal captive portal] detector tests whether the network connection requires you to log in or accept the network's terms before permitting you to use the network. This is most often the case when using a public Wi-Fi hotspot, but it can also be a corporate guest network that prompt's you to agree to it's acceptable use policy. Firefox tests if the conection is a capacitive portal by regularly connecting to http://detectportal.firefox<!-- -->.com/canonical.html. Firefox will also make connections to this URL to check if your current network supports certain technologies such as IPv6. =What to do after the captive portal check= If the page was left open by Firefox, you may simply close it. '''If this happens frequently please file a [https://bugzilla.mozilla.org/enter_bug.cgi?product=Core&component=Networking&short_desc=Captive+portal+tab+was+left+open&comment=Steps+to+reproduce&blocked=1198508&bug_type=defect Networking bug]''' and describe what happened (requires creating a Bugzilla account). =How captive portals work= Most captive portals redirect you to a login page or agree to an [https://en.wikipedia.org/wiki/Acceptable_use_policy Acceptable Use Policy - AUP]. Firefox will make automatic connections to detect these redirects and will notify you by indicating that you may need to log into the network. Normally, after you do this, the tab will be closed automatically. Occasionally, it will be kept around to display a message from the network's owners.

Captive portal checks

Firefox's captive portal detector tests whether the network connection requires you to log in or accept the network's terms before permitting you to use the network. This is most often the case when using a public Wi-Fi hotspot, but it can also be a corporate guest network that prompt's you to agree to it's acceptable use policy. Firefox tests if the conection is a capacitive portal by regularly connecting to http://detectportal.firefox.com/canonical.html. Firefox will also make connections to this URL to check if your current network supports certain technologies such as IPv6.

What to do after the captive portal check

If the page was left open by Firefox, you may simply close it.

If this happens frequently please file a Networking bug and describe what happened (requires creating a Bugzilla account).

How captive portals work

Most captive portals redirect you to a login page or agree to an Acceptable Use Policy - AUP. Firefox will make automatic connections to detect these redirects and will notify you by indicating that you may need to log into the network. Normally, after you do this, the tab will be closed automatically. Occasionally, it will be kept around to display a message from the network's owners.