Although POSIX has a standard for capabilities which I think includes CAP_NET_BIND_SERVICE, these are not required for conformance and may in some ways be incompatible with the implementation on, e.g., linux.
Since webservers like apache are not written for only one platform, using root privileges is the most portable method. I suppose it could do this specifically on linux and BSD (or wherever support is detected), but this would mean the behaviour would vary from platform to platform, etc.
It seems to me you could configure your system so that any web server could be used this way; there are some (perhaps clumsy) suggestions about this WRT apache here: NonRootPortBinding.
So why are they traditionally being started as root when afterwards everything is done to get rid of implied security issues that come with it?
They're started as root because they usually need to access a privileged port, and traditionally this was the only way to do it. The reason they downgrade afterward is because they do not need privileges subsequently, and to limit the damage potential introduced by the myriad of third party add-on software commonly used by the server.
This is not unreasonable, since the privileged activity is very limited, and by convention many other system daemons run root continuously, including other inet daemons (e.g., sshd).
Keep in mind that if the server were packaged so that it could be run as an unprivileged user with CAP_NET_BIND_SERVICE, this would allow any non-privileged user to start HTTP(S) service, which is perhaps a greater risk.
And one last desperate syntax guess pays off:
# setcap cap_net_bind_service,cap_sys_boot=+ep /usr/bin/nodejs
# getcap /usr/bin/nodejs
/usr/bin/nodejs = cap_net_bind_service,cap_sys_boot+ep
Best Answer
To remove capabilities from a file use the
-rflagThis will result in the program having no capabilities.