I do not yet have all of the hardware and networking gear set up on my network; so this is merely a description of what I'm looking to do, to gather some ideas and feedback, and then figure out how to proceed. If, after reading the details below, you want to join, or have suggestions, please let me know!
History / Ideas
I've been thinking about starting a "nerd net" for quite some time. I have many friends that use a Linux/*BSD machine at their border, and typically have some kind of services running inside the network. I'd like to link these networks together and share access to services. This opens up all kinds of possibilities...
To avoid a single point of failure, and saturation of any one network's bandwidth, we would avoid linking in a hub-and-spoke fashion. Instead, I propose that we maintain a list of active nodes (essentially, each person's gateway box) and try to maintain at least 3 active VPN connections at a time. In other words, each node on the network would have a VPN tunnel to at least 3 other nodes. It would be very useful to have control of a DNS zone for maintaining this list. Each node would have it's own A record; say, mynode.domain.com. Each time a node wants to connect to the network, it would request the A record for something like connect.domain.com, which would hand out A records of each of the registered nodes in a round-robin fashion.
Authentication will be central in this; so some knowledge of SSL will be beneficial. I, and possibly a few key others, would maintain access to a CA signing key and the nodes would be authenticated to the network via certificates signed by that CA key. Any node that you attempt to connect to should trust you based on that certificate; and, based on the certificate presented, you should trust any connection attempt with a valid, signed certificate. I, and possibly others, can assist with any certificate-based configuration issues that you might have.
To allow for a private network that's going to be potentially changing topology on a regular basis, we'll need a routing protocol, such as RIPv2. For simplicity, each network would receive it's own /24 of RFC1918 space, with the gateway box running the VPN software being the "node" on the network. Most likely, you'd want to set up split-tunneling on the gateway box so that any requests going to the private network route over the VPN and the rest of your traffic (web surfing, email, etc) goes out your normal internet connection.
With each node on the network being connected to at least 3 other nodes at any given time, that requires us to keep track of the various routes from one network to another. Instead of trying to keep track of this by hand, we could easily set up RIPv2 and announce the routes we "know". I imagine using netblocks in the 172.16.0.0/12 range, with each network having a /24 and being multi-homed (connected to 3+ other nodes), there could potentially be several routes from one network to the other. A light-weight, distance-vector routing protocol like RIPv2 seems to be a good fit; open-source implementations, simple, and proven. The route to any network from yours would be the one with the least intermittent hops.
Another, more complex, possibility would be using OSPF and OpenBSD's open-source implementation. Given that each node will have different bandwidth, this may be a good idea to try.
Services and other ideas
This would be the whole reason for the network!
I would be interested in providing several services to the network, but not publicly. For one, a Linux- or FreeBSD-based shell server with access to the internet, compilers/development tools, documentation, email (anyone remember pine+procmail?), etc. A (small-ish) public web space to let people know that you're part of the network; something like Apache's mod_userdir. A blog application accessible only from within the nerd-net.
I would also maintain the internal network's intranet site. This could be a site used to post updates of system maintenance, new services being offered/tested, and a way to maintain an up-to-date list of all of the nodes.
A private IRC server is definitely on the TODO list. Any and all bots would be allowed; if anyone would be interested in linking the IRC daemons, I'll likely be using the Blackened or UltimateIRCd.
I could provide SMTP services for the network. If we find a zone to use, I can provide email services for that zone. Technically, unlimited user@zone email addresses. I would also be willing to host DNS services for the internal network; providing dynamic DNS and a "view" for those coming in via the network.
Another service I'd consider offering would be your own PostgreSQL database for development and testing. A big part of what I envision for this network is that it'll be a big collection of computer-savvy geeks; what better place to deploy and test code than on a network inhabited solely by those with the clue to help you in debugging, vuln testing, etc.
Other possibilities include shared-CPU time using tools like distcc(1). Maybe remote storage (NFS/iSCSI)?
a public IP address to allow for incoming VPN connection requests
a Unix-like machine (Linux, Solaris, *BSD, MacOS/X)
OpenSWAN, FreeSWAN, OpenVPN, etc for creating the VPN
Zebra for RIPv2, OpenBSD OpenOSPFd for routing
The benefits of a private network are many, and extend beyond just the sharing of services. This is a chance to build a real-world, potentially large-scale network with changing topology. Any member wishing to add/configure new services or features is welcomed to; and the services could be advertised/listed on the internal network's intranet site.
Other benefits include the ability to policy-route certain traffic. For instance, I would be interested in routing my DNS traffic over the VPN to be routed out someone else's connection; it's low traffic, but my ISP mangles my DNS traffic to route to their servers regardless of what server I point to. Such configuration could even be set up where my DNS traffic goes out through a different VPN's node each time (i.e., a type of load-balancing).
As the network uses a VPN to set up, exactly what it is, a Virtual Private Network, we should seek to keep the network private. Configuring an Apache reverse-proxy, or some type of port-forward from your external IP address into the network would be frowned upon. Any need to create such accesses for the outside should be discussed with the entire group, and hopefully some sort of consensus reached.
It would also be the responsibility of each node's owner to keep the machine secure and up-to-date. Any breach of one of the nodes would lead to an open route to the network.
I will create the CA key used to sign all certificates used to access the VPN; but, as I do not wish to be the sole decider in who is allowed on the network and who is not, I plan to create a handful of sub-CA certificates to be distributed to trusted associates who may also sign certificates for potential users. If you've been given a sub-CA certificate, you're being trusted to know who you're letting into our private little clubhouse. :) Using multiple sub-CA certificates will also allow for anyone to validate who provided access for this particular user/network; and the ability to revoke access as necessary (hoping that it wouldn't ever become necessary).
A "nerd net" would be a fun project to gather a bunch of us geeks together and share services. This is the first time I'm really throwing the idea out there (beyond mentioning it to a few people here and there), so if anyone else thinks it would be fun, get ahold of me!