NTK_RFC 0003

Subject: Internet Gateway Search

This text describes a change to the Npv7. It will be included in the final documentation, so feel free to correct it. But if you want to change the system here described, please contact us first.

If the nodes are in restricted mode (compatibility with the Internet), they should share their Internet connection. This can be easily done, in fact, if a node X, connected to the Internet, activates the masquerading, it is possible for the other nodes to connect by setting as the default gateway their rnode which lead to the node X.

This can be automated by Netsukuku itself and it requires small changes in the code: it is just necessary that the nodes connected to the Internet set a flag in the qspn_pkt, in this way the other nodes will know the routes to reach the Internet.

Multi-gateways

The situation becomes a little complex when there is more than one node which shares its internet connection. Let's consider this scenario:

                   A(gw)      B(gw)
                    \          /
                     \___  ___/
                         \/
                      Ntk nodes (10.x.x.x)

A and B are nodes which shares their internet connection, we call the gateways. Let's call X the node which wants to connect to an Internet host. In this case, the nodes near to A, might find useful to use A itself to reach the Internet, the same happens for the nodes near to B. Instead, the nodes in the middle don't know what it the best choice and they might continuosly changing their gw. This means that when a tcp connection (to an inet host), which was established trough A, is then routed trough B, dies because A and B have different public IPs on the Internet.

The node X has to create an IPIP tunnel to the gateway it wants to use, and set as default gw the tunnel. In this way it is sure to use always the same gateway while the routing of the packets between it and the gw is made transparently by the other Netsukuku nodes.

Load sharing

Let's consider the previous scenario.

The node X can also decide to use both A and B to reach the Internet, using at the same time their connections! Even the gw A can use at the same time its own line and the connection of the gw B.

The procedure to implement this is what follows:

• X creates a tunnel to A and another one to B
• X adds in the routing table default route using A and B as multipath gateways. The gateway for the connections is chosen randomly.
• X adds a rule in the routing table to route all the packets of established connections trough the same gateway used to create the same connection.

The bad

The implementation of the Load sharing is very Linux specific, so it will be difficult to port it to other kernels.

MASQUERADING

Each node sharing the Internet connection (gw) has to masquerade its interfaces, so iptables must be used. In order to keep the daemon portable, NetsukukuD will launch the script found at /etc/netsukuku/masquerade.sh, which in Linux will be a simple script that executes "iptables -A POSTROUTING -t nat -j MASQUERADE".

related: ["Netsukuku RFC"]