On 2023-04-17 21:48, Carlos E.R. wrote:
You can configure your computer to prefer IPv4 or IPv6

After two decades of configuration, I don't remember what this machine is configured for. This moment I'm past bed time, so I don't remember where to check, either.

It depends on the OS.  Do a Google search.  I've never bothered with it, as it normally defaults to IPv6, which is what I prefer.

Ha! And which is the name of my computer? 😂

HAL, isn't it?  😉
Put in your DNS.  If you don't have one, use the /etc/hosts file.

I can not make the computers respond on IPv6 to names unless I write them myself in the hosts file or the DNS file, and I can not write them because they are dynamic.

One of those two addresses you mentioned is persistent.  That's the one you use.  My IPv6 prefix has been steady for over 4 years.  If your ISP did things right, the address shouldn't be changing.

I'm not using anything. The router belongs to the ISP, they do the configuration and the choices. I have no idea what it does or how.

If you're familiar with Wireshark, you can easily find out which they configured.

GSM???  Is that still available in Spain?  In North America, even 3G is disappearing.  Does your phone also have a crank on the side?  😉

Routers often use link local addresses.

Which can not be used in commands.

They can, but you also have to specify which interface it's connected to.  Here's an example, where I ping my my firewall/router:


> ping -I eth0 fe80::4262:31ff:fe12:b66c
ping: Warning: source address might be selected on device other than: eth0
PING fe80::4262:31ff:fe12:b66c(fe80::4262:31ff:fe12:b66c) from :: eth0: 56 data bytes
64 bytes from fe80::4262:31ff:fe12:b66c%eth0: icmp_seq=1 ttl=64 time=0.142 ms
64 bytes from fe80::4262:31ff:fe12:b66c%eth0: icmp_seq=2 ttl=64 time=0.149 ms
64 bytes from fe80::4262:31ff:fe12:b66c%eth0: icmp_seq=3 ttl=64 time=0.129 ms