What a captive portal is doing

A captive portal sits between you and the open internet until you accept terms, enter a room or voucher, or acknowledge an acceptable-use policy.

Businesses use it to register guests, comply with regulations, and keep track of who is online.

• Appears right after you join Wi-Fi but before other sites load.
• Common on hotel, cafe, campus, and airport networks.
• Usually clears you once you tap Accept or sign in.

How devices trigger the portal

Laptops and phones send a tiny plain-HTTP request to check if the internet is reachable. Gateways intercept that request and redirect you to the portal page.

nossl.sh mirrors those HTTP checks so the portal sees a predictable, easy-to-catch request.

• HTTP is used instead of HTTPS so the network can intercept it.
• The gateway rewrites the request to the login or terms page.
• If nothing appears, a VPN, custom DNS, or content blocker may be hiding the check.

Why captive portals get stuck

Portals rely on redirects, cookies, and DNS. If any of those fail, the splash page can loop or stall.

Opening nossl.sh gives you a timestamped header snapshot you can share with staff when the portal refuses to load.

• Private relay or VPN tools can prevent interception.
• Stale device profiles or cached redirects keep you quarantined.
• Corporate HTTPS enforcement can block the plain HTTP handshake.

Is a captive portal the same as a firewall?

No. A captive portal is a temporary gate used for sign-in or acknowledgment. After you pass it, the network’s normal firewall rules take over.

How can I get through a captive portal faster?

Join the Wi-Fi, disable VPNs or custom DNS briefly, open http://nossl.sh, follow the login prompt, then refresh the page to confirm open internet access.