should not allow UDP socket to be inherited by ifconfig

[guest]

(This is Debian bug report  http://bugs.debian.org/609751)

The UDP socket handle that is used for the main operation of the program is inherited when system() is used to execute ifconfig. The file handle should be set to close on exec or it should be closed in the child process before calling exec (which means using something other than system() ).

(gregoa@…)