Ifconfig is not always in /sbin/ifconfig #24
Description
Some years ago upstream net-tools changed ifconfig to live in /bin: ecki/net-tools@36b541c
Of course, many distros continue to put it in /sbin/, but not all.
Moreover, in some distros such as RHEL/CentOS since at least 7.x, ifconfig is not even included in a base install, only ip and the like.
I've got some simple hacks to osflags and tun.cpp to handle alternate ifconfig paths at compile time, much like ac0d27e#diff-2fc819de3e4f16d2b86d4cc7bcb7042e739f76193d7de454488cb4b33fea848d for android support.
But I think better still would be some runtime selection/fallback. One could easily compile hans on a CentOS 7 system that has optional ifconfig installed, then bring the binary to a system that has only ip and find a nasty surprise.