/usr/lib/libpacketdump/ip_58.protocol is in libpacketdump3 3.0.21-1+b1.
This file is owned by root:root, with mode 0o644.
The actual contents of the file can be viewed below.
| 1 2 3 4 | be8	integer "ICMP6: Type"
be8	integer "ICMP6: Code"
be16	hex 	"ICMP6: Checksum"
next	"icmp6"	"ICMP6: Type"
 |