Thu Jul 12 21:05:23 CEST 2018

aton(3) fun

Our dual-stacked hosts in the comapny inherit their IPv6-IIDs from their public IPv4 address. So, kenny = 217.13.66.99 is given the IPv6 address 2a00:1030:0:42::217.13.66.99 in mixed v6-dotted-quad notation. Yes, that's a possible way to spec an IPv6 address, both "in the shell" and, very convenient, in DNS zone files.

The notation will be turned into 128 bits and returned to you in canocial hex format, though:

$ host kenny
kenny.gaertner.de has address 217.13.66.99
kenny.gaertner.de has IPv6 address 2a00:1030:0:42::d90d:4263

Today I learned: yes, hex numbers are a possible way to spec an IPv4 address:

$ ping 0xd90d4263
PING 0xd90d4263 (217.13.66.99): 56 data bytes
64 bytes from 217.13.66.99: icmp_seq=0 ttl=61 time=1.982 ms
64 bytes from 217.13.66.99: icmp_seq=1 ttl=61 time=1.129 ms
^C

I was mildly surprised.

Not too much, though, because I was well aware of shortened "quads". Since a few weeks, Cloudflare operates 1.0.0.1 as a public DNS server, and

$ ping 1.1
PING 1.1 (1.0.0.1) 56(84) bytes of data.
64 bytes from 1.0.0.1: icmp_seq=1 ttl=59 time=9.51 ms
64 bytes from 1.0.0.1: icmp_seq=2 ttl=59 time=9.41 ms
64 bytes from 1.0.0.1: icmp_seq=3 ttl=59 time=9.38 ms
^C

is now perhaps the shortest way now to check for Intarweb connectivity.


Posted by neitzel | Permanent link | File under: learned