I recently upgraded from redhat 6.0 to 6.1. Since then programms like dip
or ppp cannot create their network interfaces anymore. If I start dip for
example I get the connected message in the end. Everything seems to work.
But when I use ifconfig no interface sl0 exists. When I start dip as root
it works.

I used strace to hunt the bug and found a line where a ioctl TIOGETD yields
in a permission denied.

This happens with a self build kernel 2.2.13 I had to build, since the
prebuild kernels of 6.1 and 6.0 and if I remember right 5.2 also are
compiled with Probe all Luns which crashes with my buslogic scsi
controller.

Because I had problems with nfs in 2.2.13 I tried 2.2.14 as soon as it was
released. Same problem.