๐งฑ iptables Firewall (Extended)
iptables is a lowโlevel firewall used for packet filtering and NAT.
๐ง Viewing Rules
| sudo iptables -L -v
sudo iptables -S
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๐งฉ Adding Rules
| sudo iptables -A INPUT -p tcp --dport 22 -j ACCEPT
sudo iptables -A INPUT -j DROP
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๐ง NAT Example
| sudo iptables -t nat -A POSTROUTING -o eth0 -j MASQUERADE
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๐งฑ Persistent Rules
Ubuntu:
| sudo apt install iptables-persistent
|
Save rules:
| sudo netfilter-persistent save
|
๐จ Debugging
- Check rule order
- Check default policies
- Use
iptables -t nat -L -v for NAT issues