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vrouter

Virtual router for Advanced networking class. This is a naive cleanroom implementation from a person who hasn't done any advanced router configurations or even deployed something larger than 4 port router, so expect the functionalities to very limited and probably wrong.

This is a work in progress document, so expect possible changes and improvements as vrouter is being developed. Probably won't be anything more than a proof of concept with a few advanced features.

Description

This software simulates a very simple networking router with basic data manipulation abilities and routing logic.

It is operating on three different ports:

  • 4000 - incoming traffic
  • 5000 - outgoing traffic
  • 6000 - control messages

The clients that are connected to the router are in the subnet of the router.

Incoming traffic

When incoming data arrives from the client on port 4000, it is first checked if it exists in the routing table. If it exists, the data is manipulated (if configured) and forwarded to the destination via port 5000 to a client in the subnet.

If the data is outside the subnet, a router from the R2R table is selected which matches the data destination. If not, data is declared unroutable and an adequate control message is being sent back.

Mockup of the incoming data is the following:

MESSAGE|[DATA]

where [MESSAGE] is one of the following:

  • HELLO - registers in the subnet table
  • R2R - message to register in the routing table
  • CONTINUE - message to perform routing operations on the DATA
  • END - deletes the socket from the routing table

Note that only CONTINUE accepts data. Commands without DATA must terminate with |.

DATA can be one of the following:

  • DEST:DATA - where:
    • DEST - destination IP
    • DATA - raw data that will be parsed (if required) and routed
  • EMPTY - doesn't do anything; just a placeholder for padding

Several examples of incoming data are below:

  • R2R| - registers the client as a router
  • HELLO|EMPTY - registers the client as a member of the subnet
  • CONTINUE|192.168.1.1:GOODMORNING - sends GOODMORNING to 192.168.1.1
  • END| - deletes the entry in the routing table

Outgoing traffic

There are two kinds of routing tables which determine the exit of the data:

  • subnet routing table
  • router-to-router (R2R) table

Subnet routing table is a key-value pair data store which contains the addresses of clients in the subnet, matched with their local destination addresses.

R2R table is also a key-value pair data store, but instead of subnet clients, it contains the addresses of other routers that are connected to the instance of vrouter.

When the incoming traffic gets passed over to another router, the process is repeated if needed.

Outgoing data is the same as incoming data (since router is a proxy between the incoming and outgoing data).

Control messages

Control messages represent commands sent directly to the router to alter its state, such as regeneration of routing tables and poweroff. Furthermore, This channel is used to send back to the client when the messages are undeliverable.

Control message data is the following: [COMMAND]

Where [COMMAND] is one of the following:

  • FLUSH - flushes all routing tables
  • POWEROFF - powers off the router
  • DENYALL - denies all incoming and outgoing traffic
  • ALLOWALL - allows all incoming and outgoing traffic

Data manipulation

Furthermore, vrouter contains entry points for data filtering logic as well as duplication, redirection and holding, all extendible in the mutateData(data) function.

License

MIT