Today we will learn about loopback addresses that can be reached from the outside via routing. This is useful for running services on a router In a previous post, I talked about the loopback interface and how we can locally bind services to any address in the range 127.0.
Old article I found in my bookmarks. Although I didn’t have the use for it, I thought it was interesting.
For home networks, I agree there’s usually not a need. I do it for portability reasons: I always use 192.168.0.0/24 addresses (192.168.0.0 - 192.168.0.255) for services I’m hosting on prem at home. In general, my home router is a Linux box connected directly to my ISP’s network on one interface and a switch with several VLANs on its other interface, and which has IP forwarding enabled with IP masquerade. I also use IPv6 a fair amount and receive a healthy whack of addresses from my ISP that I delegate out portions of to each VLAN. By my count I have 6 or 8 active VLANs on my home net for the adults, for work, for the kids, for the central services, for isolating untrustworthy IOT doodads, for infrastructure management, and for guests.
Most of my so-called central services have been hosted on the same Linux box that does the routing, using containers bount do tjose subnet zero IPs on the loopback. It skeeves me out a bit to do that though, so I’ve been moving that stuff over to a new applications server in a DMZ VLAN. I know what I’m doing, but I’m also incurring unnecessary risks having structured my service hosting the way I have.
The IP-on-loopback trick let’s.me move those services from a VIP on the router to an IP on the new service host without having to reconfigure everything. I just fake in some /32 routes where I need to, and the traffic goes where I want of to.
I admit up front this isn’t great discipline, but as I said I know what I’m doing and it only sounds crazy to me when I try to explain it to other people. Lol.
I appreciate the pun!
For home networks, I agree there’s usually not a need. I do it for portability reasons: I always use 192.168.0.0/24 addresses (192.168.0.0 - 192.168.0.255) for services I’m hosting on prem at home. In general, my home router is a Linux box connected directly to my ISP’s network on one interface and a switch with several VLANs on its other interface, and which has IP forwarding enabled with IP masquerade. I also use IPv6 a fair amount and receive a healthy whack of addresses from my ISP that I delegate out portions of to each VLAN. By my count I have 6 or 8 active VLANs on my home net for the adults, for work, for the kids, for the central services, for isolating untrustworthy IOT doodads, for infrastructure management, and for guests.
Most of my so-called central services have been hosted on the same Linux box that does the routing, using containers bount do tjose subnet zero IPs on the loopback. It skeeves me out a bit to do that though, so I’ve been moving that stuff over to a new applications server in a DMZ VLAN. I know what I’m doing, but I’m also incurring unnecessary risks having structured my service hosting the way I have.
The IP-on-loopback trick let’s.me move those services from a VIP on the router to an IP on the new service host without having to reconfigure everything. I just fake in some /32 routes where I need to, and the traffic goes where I want of to.
I admit up front this isn’t great discipline, but as I said I know what I’m doing and it only sounds crazy to me when I try to explain it to other people. Lol.