Show HN: ipv4.cat – your public IP address from any OS terminal | Hacker News Reader

Show HN: ipv4.cat – your public IP address from any OS terminal

about.ipv4.cat

20 pointslukejjh7 comments

It doesn't work with recent (7.66.0+) curl versions without an additional parameter, because curl somehow assumes it's a HTTP/0.9 response and these were made opt-in:

    $ curl ipv4.cat
    curl: (1) Received HTTP/0.9 when not allowed

    $ curl --http0.9 ipv4.cat
    (returns my IP)

https://github.com/curl/curl/commit/a42b0957ab31c971a79bfe55...

Yesterday we had a great thread about tools for detecting captive portals; today one about getting your IP address.

Anyway... not quite the same as this, but we have one that also supports responding with a non-200 status if a field doesn't match e.g. `curl --fail https://whoami.oya.to/tor-exit=true,ip=192.168.1.2`.

https://whoami.oya.to/about

A bit off topic but weren’t .cat domains restricted to the Catalan language? Not sure if it’s enforced though.

Sounds a lot like telnetmyip.com...

Sounds a lot like ifconfig.me...

This one is 3 letters shorter!

"Sounds a lot" like it? Sure. I've already acknowledged that on the about page. The important point of difference here is that ipv4.cat is listening for any TCP connection, not just HTTP requests. This is probably most significant for Windows since no CLI HTTP client is included out of the box (with the exception of some PowerShell cmdlets). Even a telnet client isn't included by default in Windows nowadays. This is the most universal way (as far as I can tell) to obtain a public IP address from any operating system at a terminal - just type `ftp ipv4.cat`. That's why I think this is unique.

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