# How to use RS232 --> RJ45 cable from FreeBSD?



## ORTO-DOX (Dec 12, 2013)

Good day! I have such items:

A laptop without RS232 ports, with FreeBSD installed.
A managed switch, initially managed only through the console port.
An RS232 --> RJ-45 cable like in the image above [below actually -- mod.].






How can I use that thing to login on a switch and set it up?


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## SirDice (Dec 12, 2013)

You'll need a USB to serial cable. You can then use a regular terminal program to connect to the switch.


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## ORTO-DOX (Dec 12, 2013)

Is that cable not for connecting to the RS232 port? Or is it not supported in FreeBSD?


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## SirDice (Dec 12, 2013)

ORTO-DOX said:
			
		

> Is that cable not for connecting to the RS232 port? Or is it not supported in FreeBSD?


It's a special cable. The RJ-45 at the other end is NOT Ethernet! Do NOT plug it into a network card as you will likely blow it up. The RJ-45 plugs into your switch's console port. So you need an RS-232 port on your FreeBSD machine to connect to it. Hence the need for a USB -> RS-232 converter.


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## jalla (Dec 12, 2013)

Does the switch console port have a DB9 type connector? In that case you need a different cable (DB9 to DB9 crossed serial cable), and the aforementioned USB-serial adapter on the laptop.


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## SirDice (Dec 12, 2013)

Old switches used to have the familiar DB9 serial connector, newer ones all have RJ-45 connectors (but it's still RS-232, just wired to a RJ-45). The latest HP Procurve I've worked with had, besides the RJ-45 console port, also a mini-USB connector which is basically a USB-> Serial converter built-in. I'm not too sure if that works. Getting a working USB->serial converter that works on FreeBSD may require some trial and error. Some work, some don't. The problem is that it's sometimes very difficult to find out what type of chip a particular brand/type of USB->serial cable uses. The ones that are supported should work with ucom(4) or uftdi(4).


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## ORTO-DOX (Dec 12, 2013)

Thank you all for your/the answers! So I will search for another cable.


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## wblock@ (Dec 12, 2013)

If you have a choice, the FTDI cables are better.  The cheap PL2303 cables are more common, and also work.


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