> ## Documentation Index
> Fetch the complete documentation index at: https://docs.americ.io.vn/llms.txt
> Use this file to discover all available pages before exploring further.

# ufw

> Managing firewall (iptables)

> 🗎 Refs:
> <br />[https://blog.programster.org/ufw-cheatsheet](https://blog.programster.org/ufw-cheatsheet)
> <br />[https://www.cyberciti.biz/faq/unix-linux-check-if-port-is-in-use-command/](https://www.cyberciti.biz/faq/unix-linux-check-if-port-is-in-use-command/)

#### Installation

```bash theme={null}
sudo apt update && sudo apt install ufw -y
```

#### Enable/Disable/Reload

```bash theme={null}
# Enable
sudo ufw enable
# Disable
sudo ufw disable
# Reload
sudo ufw reload
```

#### Initial setup

```bash theme={null}
# default rule - allow all outgoing, deny all incoming
sudo ufw default allow outgoing
sudo ufw default deny incoming
```

#### Start up at boot

```bash theme={null}
sudo editor /etc/ufw/ufw.conf
# Edit: ENABLED=yes
```

#### Check status

```bash theme={null}
# Simple
sudo ufw status
# Including ID
sudo ufw status numbered
```

#### Add rule

```shell theme={null}
# Allow port
sudo ufw allow $PORT_NUMBER
sudo ufw allow $PORT_NUMBER/tcp
# note: must allow the modified port of ssh first before restarting SSH

# Allow IP
sudo ufw allow from $IP_ADDRESS

# Allow IP range
sudo ufw allow from $IP/$CIDR

# Allow IP range on one port
sudo ufw allow from $IP/$CIDR to any port $PORT_NUMBER

# Block incoming requests from IP
sudo ufw insert 1 deny from $IP_ADDRESS
# note: insert 1 for on top of rule list, ufw follows the order of the rules
sudo ufw deny from $IP_ADDRESS # when there is no rule

# Block outgoing requests to IP
sudo ufw deny out from any to $IP_ADDRESS

# note: ssh is always an alias of 22
sudo ufw allow ssh
#sudo ufw allow 22
```

#### Delete rule

```shell theme={null}
sudo ufw delete $RULE_NUMBER
```

> ✍🏻**Tips**: Get `RULE_NUMBER` using [Check status](#check-status)