linux capabilities feature with non root user not able to set SO_MARK with setsockopt

Hi All,

I am having tcp server , which is running with non root user.

Trying to set the QOS on the accepted socket.

Currently it returns Permission Error as errno "Error:Operation not permitted". Trying to mark the packet with mark EE.

Observation is IPTOS and IP_PRIORITY is working fine with non root user . Only with SO_MARK I am seeing this error.

my kernel version is 4.19.183.

Any other way I can triage more like , what exact the reason for not giving the permission . ( is it only because of non root or any other reason ). I mean like any specific logs which can be referred.


Appreciate your time in reading this thread.

In case any inputs on this related , please share it.

Thanks
vlrk

This link might help or might not. I did not understand the answer.
Tim S

linux - How to resolve "setsockopt(3, SOL_SOCKET, SO_MARK, [10], 4) = -1 EPERM" Operation denied for none root users - Stack Overflow

thanks stahta01 ..I reffered this post previous , I guess he also face same issue as what I am observing.

In between can any one give exact difference between cap_set_flag and capset .

One visible difference I see is , with capset in /proc/$pid/task/$pid/status file capabilities are reflecting . But not the same with cap_set_flag.

Why this so , I don't have exact answer . This also I want to know.

Thanks