NTK_RFC 0001
Subject: Gnode contiguity
This text describes a change to the Npv7 about the collision of IPs. 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.
The real problems
A collision of IPs happens when two gnodes with the same ID are born separately, so when they meet each trough a direct link or trough other nodes many problems arise since there are some ambiguities:
- In the first case there can be nodes which have the same IP.
- In the second:
A <-> B <-> D <-> A
- After a qspn_round the node B will have two routes to reach the gnode A. But in this case the gnode A isn't a contiguous gnode, so when B wants to reach a node which belongs to A, it will send the packet using only one route which may lead to the A gnode which hasn't the wanted node.
So these are the real problems. In order to solve them it is necessary that every time two gnodes meets each other for the first time, one of them will redo the hook, in fact, this was the cause of all. When a gnode meets for the first time another gnode is like when a new node joins the network: it hooks with the other nodes. The same must be done for the gnode.
Hook of gnodes
The hook of two gnodes works in this way: only the gnode which has lesser nodes than the other will change (let's call the first gnode X and the second Y). If X and Y have the same number of nodes, the gnode which has the smaller gnode_id will change. The bnodes of X will start to re-hook, the other nodes will re-hook when they notice that their rnode which is on the best route to reach Y dies and when a new node (which was the same rnode) with the excpected IP appears. Summing up: the bnodes re-hook first, then their rnodes, then the rnodes of the rnodes of the bnodes... and so on, all the nodes of the gnode have re-hooked. When the gnode X is full the nodes which are re-hooking must choose a different gnode_id of the upper level. It is chosen in a semi-random way: it is the hash of their gnode_id (which was choosen randomly at the beginning). If the hash is a gnode_id which already exist, the hash function is reused on the hash itself.
It doesn't matter that a gnode composed by 2^24 nodes changes all its IPs, since it will happen only very few times, i.e. when the gnode of the Europe meets that of the America.
This method requires that the number of nodes present in a gnode has to be known, therefore the qspn_pkt which traverse gnodes stores also the number of nodes of each traversed gnode.
Counting the nodes
At this point all seems to be solved, but it is not. Anyone can modify the qspn, so for example the X which has less nodes than Y can fake the number, and Y will be forced to re-hook. It this happens anyone can easily force a gnode of 2^24 nodes to change its IPs! Therefore the problem to be solved now is: how can the gnode Y verify that the gnode X has really more nodes?
What is the main property of a network which has more nodes than another? The computability power!
We assume that the average computability power for a gnode of the second level or greater is constant. (a gnode of the second level can have 2^16 nodes, in the third level 2^24). Therefore the gnode of level 1 won't be checked.
Each node of the gnode which has to re-hook (in this case the gnode Y, since the gnode X is faking the qspn_pkt) will send a problem to solve to the other gnode and it wait for a very small time the reply with the solution in it. If the solution is right the node receiving it will re-hook, otherwise the gnode X will be banned and excluded from all the qspn floods. Only one challenge each T time can occur, where T is proportional to the size of the Y gnode. So say that Y has 16milions IPs, if it has already sent a challenge it will send another after 10 minutes.
Another bug
But this system leaves opened another kind of attack: the gnode X can target a single node in Y, replying only to its reply and making it re-hook. In order to prevent this the nodes act in this way:
- When a node hooks it creates a RSA key pair, then its rnodes get its public key.
- When a node receives a reply to the problem it sends broadcast inside its gnode it signing it with its public key. When its rnodes
receive the pkt check the signature. If it is valid they update the counter of received replies for the problems sent, then they substitute the signature with their own. The packet will propagate until it reaches all the nodes of the gnode.
- The nodes will start to rehook only when all the replies will be
received (during the wait time). Since it is not possible that all the reply are received it is allowed that 10% of replies are lost.
The problem to solve sent by the nodes is:
- f(x) mod k
where k is a random number between 216 and 232.
f(x) is a function which is not easily computable with mod k. When x gets bigger the computation time increases. We are still deciding on what f() function using.
ANDNA changes
If a same hostname is registered in two separeted gnodes what happens when they meet? Which node will mantain the hostname?
The node which is in the greater gnode wins: the hash_nodes of the smaller gnode, which re-hooks, will reset their uptime counter, in this way when they receive the update request from the node (which has changed its IP and must update its hname), they ask to the other gnode for the old andn_caches.
And that's all
That's all folks.
Alpt, Katolaz, Mancausoft, Uscinziatu