/usr/share/grc/conf.mtr is in grc 1.11.1-1.
This file is owned by root:root, with mode 0o644.
The actual contents of the file can be viewed below.
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 | #ip address
regexp=\d{1,3}\.\d{1,3}\.\d{1,3}\.\d{1,3}
colours=green
=======
# %
regexp=[0-9]{1,2}\.\d{1}%
colours=yellow
=======
# unknow host
regexp=\?\?\?
colours=red
=======
# Packets/Pings
regexp=(Packets|Pings)
colours=bold green
|