Second, openWRT development background
When Linksys released the WRT54G/GS source code, many different versions of firmware appeared on the Internet to enhance the original functions. Most firmware 99% uses Linksys source code, with only 1% added. Each firmware is designed for a specific market. This has two disadvantages. The first is that it is difficult to integrate the advantages of various versions of firmware, and the second is that this version is getting farther and farther away from the official release of Linux.
OpenWrt chose another way. It starts from scratch and adds all kinds of software bit by bit to make it close to the function of Linksys firmware. The success of OpenWrt is that its file system is writable, and developers don't need to recompile it after each modification, making it more like a small Linux computer system.
Third, OpenWrt function
1, openwrt can be used as a client to connect other wifi as a WAN, and then create its own wifi as a LAN, which is equivalent to a wired WAN port. You can surf the Internet through wifi without plugging in a network cable. Other firmware does not seem to have this setting method. I wonder if I didn't find it. Other firmware can only relay other wifi, the client actually connects to this relayed wifi, and the ip is also assigned by the superior relaying wifi, so it is impossible to create a subnet through this router. The advantage of openwrt is to connect to the Internet through wifi, and create a subnet by itself, which can map ports, speed limits and so on.
2.SSH tunnel
OpenWrt includes an SSH server, so you can access its terminal. After exposing its SSH service to the network (don't forget to encrypt it with key authentication instead of weak password), you can use SSH tunnel encryption for remote connection and access. This allows you to access some websites that can only be accessed in China through public Wi-Fi.
3. Build VPN
SSH tunnel and VPN are similar in many ways, but you can still build your own VPN on OpenWrt route.
4. Install BitTorrent client.
If you have a specific network attached storage (NAS), or a router with USB ports and USB devices, you can think of the router as a BitTorrent client.
5. Run the server software
OpenWrt's software source contains software packages that can make it a web server, such as IRCserver, BitTorrenttracker and so on. You may use a router, so why not just use this router as a server? Routers consume much less power than computers, so it is wise to regard them as lightweight servers.
6. traffic shaping service
OpenWrt allows you to shape routed packets, check their quality of service, and give priority to the appropriate packets. You can even give priority to assigned packets to assigned computers and delay processing packets assigned to other computers.
7. Create a VIP network
OpenWrt's wiki has instructions on how to set up a special wireless network for guests. For security reasons, this network is separate from your main network. You can even limit the speed of the VIP network.
8. Capture and analyze network traffic.
You can use tcpdump to record all packets passing through the router. Then you can share it on the network or open it with a tool like Wireshark, and then analyze your network traffic and behavior.
Fourth, openWRT features
OpenWRT is a highly modular and automated embedded Linux system with powerful network components and expandability, which is often used in industrial control devices, telephones, small robots, smart homes, routers and VOIP devices. At the same time, more than 100 compiler software is provided, and the number is increasing. OpenWrtSDK simplifies the process of developing software.
OpenWRT is different from many other distributions used in routers. This is a fully functional router operating system written from scratch and easy to modify. In fact, this means that you can use the functions you want without adding other burdens, and the linuxkernel that supports these functions is far newer than most distributions.