Server without the ethernet sheild

I'm considering making a server out of my board, but I wish not to use the ehternet shield, not because I'd have to buy additional hardware, but I'd like to push the limits of Arduino and learn a thing or two about networking. I've found several projects that do this already, but they all require a computer between them and the internet (SLIP). My ultimate goal would be to use a simple ehternet port and wire the lines to pins, so the only extra hardware would be the RJ45 port.

Is that possible? Emulate the whole TCP/IP protocol or a subset of it at least to, for example, read a sensor value over the internet?

Solenoid: Is that possible? Emulate the whole TCP/IP protocol or a subset of it at least to, for example, read a sensor value over the internet?

You're going to need a couple more layers than that...