binding socket fails when run under ptrace?

[Bryn M. Reeves]

On 07/26/2011 01:59 PM, Tom Horsley wrote:
> tomh> strace -o working.trace rsh tomh date
> rcmd: socket: Permission denied

It's presumably being having its capabilities dropped because you are ptracing
an executable with the cap_net_bind_service capability as an unprivileged user
(if it wasn't it would be a security hole as a regular user could use a debugger
to bind arbitrary privileged ports).

Older releases had the same behaviour when ptracing SUID binaries - this is the
same reason you cannot strace the ping command (requires a raw socket so is
either SUID or cap_net_raw).

Regards,
Bryn.