# IP Tables

* Allows system administrators to define rules that control how incoming and outgoing traffic is handled
    

---

Important commands:

iptables --version - Command to check iptables version

---

iptables -L - To check the list of input and output traffic

---

iptables -A INPUT -p tcp -s [**172.xx.xxx.xxx**](http://172.xx.xxx.xxx/) --dport 22 -j ACCEPT

* Command permits SSH access *only* from the given IP([**172.xx.xxx.xxx**](http://172.xx.xxx.xxx/)**)** address. This is a solid approach for limiting SSH access to trusted sources — a common best practice for hardening servers.
    

* \-A INPUT: Appends the rule to the INPUT chain, which handles packets destined for the local system.
    
* \-p tcp: Specifies that the rule applies to TCP packets.
    
* \-s 172.xx.xxx.xxx: Source IP address. Only packets coming from this IP will be matched.
    
* \--dport 22: Destination port 22 — typically used for SSH.
    
* \-j ACCEPT: The action to take — allow the packet through.
    

---

iptables -A INPUT -s 192.168.1.100 -j DROP - Command to drop all incoming traffic from a specific IP

---

iptables -A OUTPUT -j ACCEPT - To allow all outgoing traffic