DN42 is an experimental network , where everyone helps everyone. Nobody is going to blame you if you screwed up. You may seek help at DN42's IRC channel , mailing list or the unofficial Telegram group . Since DN42 is a network for experimentation, a lot of relatively inexperienced users also participate in it. Therefore, occasionally an inexperienced user may misconfigure his/her system and impact the whole DN42 network or even shut it down. As a more experienced user, here I will teach new users about some operations that can kill the network and about defense against such misconfigurations that everyone can set up against peers. WARNING: You should not actually perform these operations in DN42. You should focus more on protecting yourself against them....

DN42, aka Decentralized Network 42, is a large, decentralized VPN-based network. But unlike other traditional VPNs, DN42 itself doesn't provide any VPN exits, which means it doesn't allow you to bypass Internet censorships or unlock streaming services. On the contrary, the goal of DN42 is to simulate another Internet. It uses much of the technology running on modern Internet backbones (BGP, recursive DNS, etc), and is a great replica of a real network environment. In short, DN42 is: NOT suitable for users only seeking privacy protection or bypassing censorship NOT suitable for users consuming large amounts of bandwidth/data, such as for unlocking streaming services IS suitable for users learning about networking, practicing configuration of servers and routers,...

Changelog 2020-10-01: Add warning to not filter private ASNs within the internal network 2020-06-07: Add limitations of Bird confederation and a way to simulate confederation 2020-05-17: Initial version Comparison of BGP Interconnection Schemes within an ISP Most ISPs, or Internet Service Providers, use the BGP protocol to exchange their route information. Each ISP will obtain an ASN (Autonomous System Number) from the regional NIC (Network Information Center, e.g., APNIC, RIPE), like China Telecom's ASN is 4134 for example. Then, ISPs connect their boundary routers via physical links (copper line, fiber, satellite link, etc.), and configure BGP protocol on the boundary routers, so they will tell the other part that: "I'm AS4134, and I can provide access to the IP block of 202.101.0....

2020-03-16 Notes There is an updated scheme compared to this post, see Sharing Network Namespace Among Docker Containers for Bird Anycasting . It is suggested to read only the concept explanations in this post, and use the above scheme instead for deployment. What's Anycast The commonly used routing protocol on Internet, the BGP, works like this: I own an IP range, 172.22.76.104/29, on DN42. With a BGP software like BIRD, I "announce" that my server has access to IP range 172.22.76.104/29. Servers with peering to me will record this message: "Over this path, I can access 172.22.76.104/29 which is 1 step away." These servers continue to announce to others with peering to them: "This server is 1 step away from the source of 172.22.76.104/29." Similarly,...