NAT

🚀 Network Address Translation (NAT) Network Address Translation (NAT) is a technique used in IPv4 networks to manage the shortage of public IP addresses and provide security by hiding internal network structures. NAT is typically implemented on routers or firewalls and allows a single public IP address to represent multiple devices in a private network. Types of NAT: Static NAT: Maps a private IP address to a specific public IP address. Each internal device has a fixed corresponding public IP. Dynamic NAT: Maps a private IP address to a pool of public IP addresses. When an internal device initiates a connection, the router selects an available public IP from the pool. Port Address Translation (PAT): Also known as Overloading, it maps multiple private IP addresses to a single public IP address using different port numbers to differentiate between the connections. 🧠 How NAT Works Translation Process: When a device in a private network sends data to the internet, the NAT device modifies the source IP address in the packet header from the private IP to the public IP. The device keeps track of the connection in a translation table. ...

In virtualized environments, it’s common to have a VM running behind NAT, especially when using tools like QEMU, VirtualBox, or cloud labs. This setup means the VM can reach the host, but the host cannot directly initiate connections to the VM — including to web services like the Proxmox web GUI running on port 8006. Fortunately, this limitation is easy to bypass using reverse SSH tunneling. 🧠 Objective We want to: ...

🧩 VM Behind NAT? 🖥️ Scenario Your VM is running as root user. Your host machine has a user named rohan. The VM is behind NAT — it can talk to the host, but the host can’t directly talk to the VM. You want the host to be able to connect to the VM anyway. No worries — you can use a reverse SSH tunnel to solve this! ✅ Goal Allow your host (rohan@host) to SSH into your VM (root@vm) even though the VM is behind NAT. ...