# Serial to ethernet adaptor: SLIP?



## Imanol (Aug 11, 2012)

I've just set up a server into an old P4 and it currently has no ethernet NIC's. I've bought a pair on ebay, but until they get here, I'd like very much to use a weird adaptor I found once, it has a RS232 serial plug on one end, and a RJ-45 plug on the other.

My server is headless, but it has 2 serial ports, so my goal is to use one of the serial ports for networking.

I don't know the pinout of the cable, but let's guess it should work.

How can I make it work? I've installed FreeBSD 9 and it seems that it SLIP is not supported anymore, and I don't even know if SLIP is what I'm looking for.

I'd appreciate some help 

Thanks for your attention.


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## Uniballer (Aug 11, 2012)

The common ways to run TCP/IP networking over asynchronous serial lines were SLIP and PPP.  Both ends must support it.  SLIP is really basic with very few options and no option negotiation.  PPP is a lot more complicated and capable.

The presence of an RJ-45 connector does not necessarily imply ethernet, as these connectors originated in the telephone industry and were used for many proprietary purposes over the years.  Are there any markings on the "weird adapter" that might help identify it?


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## Imanol (Aug 11, 2012)

It says (not in order) "copartner E11932-U 26AWG AWM2464"

A quick google search of those words show it's just a generic cable (I mean, it's just a cable, no jacks), used for USB adapters, sata cables, etc...

No relevant words or markings of any type, it's just a cable like this:

RS232FEMALE----(cable)---RJ45MALE

I want to hook it up to my switch, which connects to my DHCP server in order to get some networking...

Any suggestions?


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## kpa (Aug 11, 2012)

I bet that cable is for a cisco router or similar, some of the models had an RJ45 connector for serial console. I don't see how you could convert a serial port to ethernet though.


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## Uniballer (Aug 11, 2012)

Yeah.  Wait for the NICs.

If it is just cable then there is no chance that you are going to get this to work.  Conversion from SLIP/PPP to ethernet requires some electronics and quite a bit of protocol encapsulation/decapsulation.  You would most likely need a box of some sort that includes a microprocessor, not just a length of cable with different connectors at each end.


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## Imanol (Aug 11, 2012)

That's what I thought too, since RS232 and ethernet are quite different protocols they couldn't just work without some electronics in the middle (and there are none).

Since I don't know where that cable came from (it found it when cleaning my room), god knows where it's from, maybe it's from some cisco hardware as kpa said.

Thank you all for your help, I'm gonna wait for the NIC's and mark this as solved.

EDIT: I can't recall how to mark threads as solved, can anyone do it or post how to?


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## Deleted member 9563 (Aug 11, 2012)

Imanol said:
			
		

> I want to hook it up to my switch, which connects to my DHCP server in order to get some networking...
> 
> Any suggestions?



You can connect with serial directly to a computer in between. I often connect vintage DOS boxes to the internet by running PPP on the DOS box and using a serial cable to any on-line Linux box set to port forwarding. This avoids using a network card on the originating machine. Any old machine with both a serial and an ethernet port can be used since the requirements are minimal. You need to run pppd on this in-between box which can then connect with ethernet to the switch or whatever you want.


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## Imanol (Aug 12, 2012)

Yes, I remember doing that at the lab on my university, connecting two linux boxes through serial port, but I don't have any more null-modem cables or free serial ports on any box.

I've gotten internet at least, I set up an improvised router with a spare netbook with debian: dhcp, hostapd and some NAT forwarding. All provisional thankfully...


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