iodine

iodine - https://code.kryo.se/iodine This is a piece of software that lets you tunnel IPv4 data through a DNS server. This can be usable in different situations where internet access is firewalled, but DNS queries are allowed. COMPILING To compile iodine you need meson. Run the following commands to compile inside the build directory: meson setup build cd build ninja To build and run the tests you need the check library. Start them by running ninja test inside the build directory. QUICKSTART Try it out within your own LAN! Follow these simple steps: On your server, run: ./iodined -f 10.0.0.1 test.com. If you already use the 10.0.0.0 network, use another internal net like 172.16.0.0. Enter a password. On the client, run: ./iodine -f -r 192.168.0.1 test.com. Replace 192.168.0.1 with your server's ip address. Enter the same password. Now the client has the tunnel ip 10.0.0.2 and the server has 10.0.0.1. Try pinging each other through the tunnel. Done! :) To actually use it through a relaying nameserver, see below. HOW TO USE Note: server and client are required to speak the exact same protocol. In most cases, this means running the same iodine version. Unfortunately, implementing backward and forward protocol compatibility is usually not feasible. Server side To use this tunnel, you need control over a real domain (like mydomain.com), and a server with a public IP address to run iodined on. If this server already runs a DNS program, change its listening port and then use iodined's -b option to let iodined forward the DNS requests. (Note that this procedure is not advised in production environments, because iodined's DNS forwarding is not completely transparent, for example zone transfers will not work.) Alternatively you can forward the subdomain from your DNS server to iodined which must then run on a different port (-p). Then, delegate a subdomain (say, t1.mydomain.com) to the iodined server. If you use BIND for your domain, add two lines like these to the zone file: t1 IN NS t1ns.mydomain.com. ; note the dot! t1ns IN A 10.15.213.99 The NS line is all that's needed to route queries for the t1 subdomain to the t1ns server. We use a short name for the subdomain, to keep as much space as possible available for the data traffic. At the end of the NS line is the name of your iodined server. This can be any name, pointing anywhere, but in this case it's easily kept in the same zone file. It must be a name (not an IP address), and that name itself must have an A record (not a CNAME). If your iodined server has a dynamic IP, use a dynamic DNS provider. Simply point the NS line to it, and leave the A line out: t1 IN NS myname.mydyndnsprovider.com. ; note the dot! Then reload or restart your nameserver program. Now any DNS queries for domains ending in t1.mydomain.com will be sent to your iodined server. Finally start iodined on your server. The first argument is the IP address inside the tunnel, which can be from any range that you don't use yet (for example 192.168.99.1), and the second argument is the assigned domain (in this case t1.mydomain.com). Using the -f option will keep iodined running in the foreground, which helps when testing. iodined will open a virtual interface ("tun device"), and will also start listening for DNS queries on UDP port 53. Either enter a password on the commandline (-P pass) or after the server has started. Now everything is ready for the client. If there is a chance you'll be using an iodine tunnel from unexpected environments, start iodined with a -c option. Resulting commandline in this example situation: ./iodined -f -c -P secretpassword 192.168.99.1 t1.mydomain.com Client side All the setup is done, just start iodine. It takes one or two arguments, the first is the local relaying DNS server (optional) and the second is the domain you used (t1.mydomain.com). If you don't specify the first argument, the system's current DNS setting will be consulted. If DNS queries are allowed to any computer, you can directly give the iodined server's address as first argument (in the example: t1ns.mydomain.com or 10.15.213.99). In that case, it may also happen that any traffic is allowed to the DNS port (53 UDP) of any computer. Iodine will detect this, and switch to raw UDP tunneling if possible. To force DNS tunneling in any case, use the -r option (especially useful when testing within your own network). The client's tunnel interface will get an IP close to the server's (in this case 192.168.99.2 or .3 etc.) and a suitable MTU. Enter the same password as on the server either as commandline option or after the client has started. Using the -f option will keep the iodine client running in the foreground. Resulting commandline in this example situation, adding -r forces DNS tunneling even if raw UDP tunneling would be possible: ./iodine -f -P secretpassword t1.mydomain.com From either side, you should now be able to ping the IP address on the other end of the tunnel. In this case, ping 192.168.99.1 from the iodine client, and 192.168.99.2 from the iodine server. MISC. INFO IPv6 The data inside the tunnel is IPv4 only. The server listens to both IPv4 and IPv6 for incoming requests by default. Use options -4 or -6 to only listen on one protocol. Raw mode will be attempted on the same protocol as used for the login. The client can use IPv4 or IPv6 nameservers to connect to iodined. The relay nameservers will translate between protocols automatically if needed. Use options -4 or -6 to force the client to use a specific IP version for its DNS queries. If your server is listening on IPv6 and is reachable, add an AAAA record for it to your DNS setup. Extending the example above would look like this: t1 IN NS t1ns.mydomain.com. ; note the dot! t1ns IN A 10.15.213.99 t1ns IN AAAA 2001:db8::1001:99 Routing It is possible to route all traffic through the DNS tunnel. To do this, first add a host route to the nameserver used by iodine over the wired/wireless interface with th