Permission Error of Tun devices

I'm running several applications use tun devices as a non-root user. My hostname.tunX file is like:

# /etc/hostname.tun0
inet 192.168.37.4 255.255.255.254 NONE
dest 192.168.37.3
mtu 1436
!/sbin/chown tunuser:tunuser /dev/\$if

They worked great until recently. I noticed causal permission error (error number 13) leading to the applications crashed. It occurs like once per 2 ~ 3 days after I upgraded the system to 6.8. Does anyone have clues about the reason of permission denials?


Siegfried
siegfried.levin@gmail.com