firewall ubuntu/backtrack

For active firewall you can typing "ufw" COMMAND

Commands:

enable (enables the firewall)
disable (disables the firewall)
default ARG (set default policy)
logging LEVEL (set logging to LEVEL)
allow ARGS (add allow rule)
deny ARGS (add deny rule)
reject ARGS (add reject rule)
limit ARGS (add limit rule)
delete RULE|NUM (delete RULE)
insert NUM RULE (insert RULE at NUM)
reset (reset firewall)
status (show firewall status)
status numbered (show firewall status as numbered list of RULES)
status verbose (show verbose firewall status)
show ARG (show firewall report)
version (display version information)

Application profile commands:
app list (list application profiles)
app info PROFILE (show information on PROFILE)
app update PROFILE (update PROFILE)
app default ARG (set default application policy)