til/unix/determine-ipv4-and-ipv6-public-ip-addresses.md

Determine ipv4 And ipv6 Public IP Addresses

There are a number of ways to do this. The one that I've settled on is sending a curl request to a public URL that was specifically set up to echo back the public IP of the device making the request. There are many such URLs, but the one that I tend to use is ifconfig.io.

When I run this as is, I get something like the following which you may recognize as an ipv6 IP address.

$ curl ifconfig.io
2001:db8:3333:4444:5555:6666:7777:8888

This is because if ipv6 is available, like it is for me, curl is going to prefer that.

Now, if I'm trying to track down specifically my ipv4 address, I can use the -4 flag (or --ipv4).

$ curl -4 ifconfig.io
73.23.45.157

Similarly, I could explicitly specify ipv6 with -6 or --ipv6.

See man curl for more details.