Firewall on Ubuntu
From Gruff Goat Wiki
On Ubuntu, I use the built in firewall, iptables, and manage the initial setup using UFW - Uncomplicated Firewall.
Initial Settings
ufw default deny # Default rule
ufw allow ssh # Allow all ssh traffic on port 22 ufw allow ftp # Allow all ssh traffic on port 21 ufw allow www # Allow all ssh traffic on port 80 ufw allow 8080 # Allow JAVA
ufw limit ssh # Connection rate limiting ufw allow smtp # Allow all ssh traffic on port 25 ufw allow pop3 # Allow all ssh traffic on port 110 ufw allow imap2 # Allow all ssh traffic on port 143 ufw allow https # Allow all ssh traffic on port 443 ufw allow imaps # Allow all ssh traffic on port 993 ufw allow pop3s # Allow all ssh traffic on port 995 ufw allow 587 # Allow SMTP Auth Submission
ufw logging on ufw enable # Turn the firewall on
ufw status # Check firewall status