[kgns]

i indeed changed server machine. old one had debian 8.7.1 on it, and new one ubuntu 16.04.3. so i guess its enabled by default on debian distro, but disabled on ubuntu.

this should make it work for current session:

echo 0 > /proc/sys/kernel/yama/ptrace_scope

this should make it work for every session (even after reboot)

editing /etc/sysctl.d/10-ptrace.conf

changing
kernel.yama.ptrace_scope = 1
to
kernel.yama.ptrace_scope = 0

is this correct?