In a nutshell
The core of the Linux firewall is the netfilter kernel module. To add or remove firewall rules you need the "iptables" application (should already be installed).  where is the  [ ... ]

No file on a server should have o+w permissions (at least I can't think of a reason).The command to find all world writable files on system is: # find / -perm -0002  -type f -print
This command will [ ... ]