tr -s \[:blank:] \ </etc/fstab | # squeeze all tabs/spaces to 1 space
sed 's/^#/ # # # # # #/' | # create 6 tiny comment fields
column -t | # get columns
sed '/^\( *#\)\{6\}/{s//#/;s/ */ /g;}' # fix and squeeze spaces for comments
Верно:
iptables -A INPUT -p tcp -s 10.0.0.0/8 --dport 22 -j ACCEPT
iptables -A INPUT -p tcp -s 172.16.0.0/12 --dport 22 -j ACCEPT
Объяснение здесь:https://en.wikipedia.org/wiki/Private_network