> Having complete control of TCP/IP in userland like this, with so little code, is so valuable I feel like there needs to be some special name for the technique.
Many years ago, when we could take always-on desktop PCs more or less for granted, I developed a product that let the user connect back to their home PC from another PC, to stream music from home or grab a file (this was also pre-Dropbox). NAT was already ubiquitous by this point, and Windows XP SP2 (first version with Windows Firewall) came out that year, so I knew it couldn't just make a direct TCP connection to the user's home PC. So I did a stupid relay implementation, where both the client and the home server (that's what we actually called the tray applet on the home PC) made outgoing TCP connections to our central server, which would relay packets back and forth. If I'd had access to a TCP-in-userspace thing like the gvisor network stack, I could have run TCP end-to-end, the way it's meant to be used. It almost makes me want to reimplement that old system using Go and WireGuard, even though the functionality is basically irrelevant in today's world.
Many years ago, when we could take always-on desktop PCs more or less for granted, I developed a product that let the user connect back to their home PC from another PC, to stream music from home or grab a file (this was also pre-Dropbox). NAT was already ubiquitous by this point, and Windows XP SP2 (first version with Windows Firewall) came out that year, so I knew it couldn't just make a direct TCP connection to the user's home PC. So I did a stupid relay implementation, where both the client and the home server (that's what we actually called the tray applet on the home PC) made outgoing TCP connections to our central server, which would relay packets back and forth. If I'd had access to a TCP-in-userspace thing like the gvisor network stack, I could have run TCP end-to-end, the way it's meant to be used. It almost makes me want to reimplement that old system using Go and WireGuard, even though the functionality is basically irrelevant in today's world.