For everyone using computers and the internet, the word “localhost” is familiar. But why, despite using it daily, do we often not understand how it works? In this article, we’ll address this curiosity and explain in detail how localhost operates to enhance your understanding.
Definition of localhost
When we say localhost, it refers to the address of our own computer. This address consistently uses the IP address 127.0.0.1. Thus, sending data to localhost means the data does not go outside but returns directly to our computer. It’s like talking to yourself, with your computer listening to your own words.
Network Interface (NI)
A network interface is a device necessary for a computer to connect to a network. Wi-Fi, LAN cards, etc., fall under this category. These devices are recognized by the OS, and each is assigned a unique NI number. This number can be checked using terminal commands like ifconfig or ipconfig /all.
Loopback NI
Every computer has a virtual device called Loopback NI. This device is not a physical one and handles IP addresses in the 127.0.0.0/8 range. Among these, 127.0.0.1 is the most commonly used address, which signifies localhost. Therefore, thanks to Loopback NI, we can use localhost.
Packet Flow of localhost
- Sending data from an app: A web browser sends a request to http://127.0.0.1.
- Packet delivery to local: It goes to the loopback NI via the TCP/IP stack.
- Receiving request by server app: The local server app receives the request and generates a response.
- Response packet’s loopback path: The response packet follows the same path back to the browser.
Conclusion
Although localhost is a concept we use daily, understanding its operation can significantly help in problem-solving. We hope this article resolves your curiosity and enhances your understanding of networks.