open("/proc/net/dev", O_RDONLY) = 6
open("/proc/net/if_inet6", O_RDONLY) = 6
open("/proc/net/if_inet6", O_RDONLY) = 6
open("/proc/net/if_inet6", O_RDONLY) = 6
and see fd id is 6, you can also see the fd in your /proc/<pid>/fd:
ls -al /proc/<pid>fd for a particular process give:
>ls -al /proc/2187/fd
total 0
lr-x------ 1 xxx xxx 64 Dec 16 07:26 0 -> /dev/null
l-wx------ 1 xxx xxx 64 Dec 16 07:26 1 -> /dev/null
lrwx------ 1 xxx xxx 64 Dec 16 07:26 10 -> anon_inode:[eventfd]
lrwx------ 1 xxx xxx 64 Dec 16 07:26 11 -> /dev/dri/card0
registration of /proc happened when /proc is being initialized and created:
fs/proc/root.c:proc_root_init()
and the function for network is proc_net_init() inside fs/proc/proc_net.c.