ip.bzh
Brezhoneg

Network tools

IP address or domain lookup

Your connection

DNS leak test

Shows which DNS servers actually resolve your requests, and how they behave: subnet passed on, defences against forged answers, minimisation, DNSSEC. With a VPN, they should not belong to your usual internet provider.

    WebRTC leak test

    WebRTC lets a website discover your device's real address, even behind a VPN. This test compares the address WebRTC sees with the one your connection to this site uses.

    Open port test

    Checks from the Internet whether TCP ports of your public IP address accept connections, up to 10 at a time. Only your own address can be tested.

    Tests from our servers

    Ping

    Sends 4 ICMP packets from our servers (not from your connection) to the address or name you enter.

    Traceroute

    Shows the routers crossed from our servers to the destination.

    Domains and e-mail

    DNS propagation

    Asks six big public resolvers and the domain's own DNS servers the same question: is a change already seen everywhere, or do caches still hold the old answer?

    E-mail header analyzer

    Paste the headers of a message (“Show original” or “View source” in your mail client): sender, SPF, DKIM and DMARC results, and the route of the message server by server, with the time each step took.

    The analysis runs in your browser: the headers are sent nowhere (without JavaScript, the server reads them and forgets them at once).

    Calculators

    CIDR calculator

    Computes the network, mask and address range of an IPv4 or IPv6 subnet. The calculation runs in your browser (on the server, without keeping anything, if JavaScript is off).

    IPv6 generator

    Generates a random private prefix (ULA, fd00::/8) or splits your own prefix into subnets, with a random address. Everything happens in your browser.

    Frequently asked questions

    How can I tell if my VPN leaks?

    Run the DNS leak test: the resolvers shown must not belong to your internet provider. Run the WebRTC test too: it should only reveal the VPN's address, not your real one.

    Why do ping and traceroute start from your servers?

    Measurements are made from ip.bzh to the target, not from your connection: they tell you whether a machine is reachable from the Internet, not how good your own access is.

    How do I test whether a port is open?

    The port test connects to your own public IP address on the chosen port and reports whether it is open, closed or filtered by a firewall. It cannot be used to test other machines.

    What does CIDR notation mean?

    192.168.1.0/24 is a network whose first 24 bits identify the network. The calculator works out the mask, the address range, the broadcast address and the number of hosts.

    Is my IP address on a blocklist?

    Search for it: ip.bzh asks Spamhaus, SpamCop, PSBL, Mailspike and DroneBL. A listed address gets its e-mails refused or sent to spam. Spamhaus's PBL, on the other hand, merely lists home connections, which should not send mail directly: being on it is normal.