in-addr

A simple tool to take a subnet mask and print out the in-addr reverse order to stdout.

This simplifies creating entire network ranges of files for DNS reverse lookup etc.

IPv4

$ ./ptr generate 192.168.15.99/20
0.168.192.in-addr.arpa.
1.168.192.in-addr.arpa.
2.168.192.in-addr.arpa.
3.168.192.in-addr.arpa.
4.168.192.in-addr.arpa.
5.168.192.in-addr.arpa.
6.168.192.in-addr.arpa.
7.168.192.in-addr.arpa.
8.168.192.in-addr.arpa.
9.168.192.in-addr.arpa.
10.168.192.in-addr.arpa.
11.168.192.in-addr.arpa.
12.168.192.in-addr.arpa.
13.168.192.in-addr.arpa.
14.168.192.in-addr.arpa.
15.168.192.in-addr.arpa.

IPv6

$ ./ptr generate 2001:db8:abcd:1234::1/56
0.0.2.1.d.c.b.a.8.b.d.0.1.0.0.2.in-addr.arpa.
1.0.2.1.d.c.b.a.8.b.d.0.1.0.0.2.in-addr.arpa.
2.0.2.1.d.c.b.a.8.b.d.0.1.0.0.2.in-addr.arpa.
3.0.2.1.d.c.b.a.8.b.d.0.1.0.0.2.in-addr.arpa.
4.0.2.1.d.c.b.a.8.b.d.0.1.0.0.2.in-addr.arpa.
5.0.2.1.d.c.b.a.8.b.d.0.1.0.0.2.in-addr.arpa.
6.0.2.1.d.c.b.a.8.b.d.0.1.0.0.2.in-addr.arpa.
....

Building

go build -o ptr cmd/in-addr/main.go