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Serial Console on Sun UltraSparc servers


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First of all you need null model cable. Specialists of old school can solder their own, but this art is essentially lost :-).

Sun server usually come with one crossover 9-pin connector (silver colored, Sun Part No. 530-3100-01). Don't throw it out when you get with the server ;-). This connector can be used with a regular Ethernet cable. That's the most convenient solution for server rooms as you can use cable of any necessary length to position your laptop conveniently or get to the desktop or workstation (if connecting to a Sun workstation or server, use 25 pin connector --- Sun Part No. 530-2889-03 or equivalent).  You can also create your own or buy ready made cable

Sun servers have two management port: one serial management  (marked SER MGT) and one Net management ( marked NET MGT).  You need to use serial management port. It has Ethernet connector.

You can use iether sun connector or cables used for managing network devices like Cisco.  Cisco "blue cable" is probably the most common cable of this type.


Net management port is used to connect to ALOM (ILOM on newer Sun servers like SPARC T4-1 Server) and you need to configure it before that.

Select suitable source for your serial connection

There are several ways to use serial console for connecting to Sun servers

Verify preconditions

No keyboard should be connected to Sun server/workstation on which you plan to use serial console. Sun machines on power-up check the presence of the keyboard. If something is plugged in, they assume the console input device is the keyboard. If it doesn't see any keyboard, it redirects console input/output to serial port "A".

Whether or not the Sun server has a  videocard ("framebuffer" card) installed is irrelevant. Modern Sun workstations have a framebuffer built in. That's why the test is always done for the keyboard  presence.

If you use USB to serial convertor you need to test it first with some workstation to be sure that it works. Many of them don't. Problem can be Windows 7 driver (especially on Windows 64) or the quality of cable. Often you can borrow such cable from network engineers, who use then for connecting to CISCO routers. In this case you can consider the cable tested and it should work for you as well.  If you need to buy such a cable it is also prudent to buy the same as network engineers use, even if it cost slightly more. 

Do not connect a keyboard to the Sun machine if you want to use serial console

If you SHUT OFF YOUR TERMINAL, while it is connected to a running Sun machine, you send a "break" signal via the serial line and the Sun will jump back into the OK prompt, halting the OS. This can cause  considerable confusion.

Using Window Hyperterminal

Note: you can upgrade to free version 6.3 (non-commercial use)

Try  these COM1 port settings:

I'm going to use a Dell C600 laptop an an example. The laptop has a 9pin serial port at the back that corresponds to Serial port 1 (SER 1). In other cases you need first to verify that you're "speaking" to the correct port (you can do this using for example serial mouse and disconnecting your current mouse). 

Using windows terminal you can use VT-100 or better.

You can connect to Sun server that has no keyboard or display attached anytime. sometimes you need to press enter one of two times to see the output. You can disconnect anytime by disconnecting cable (do not close you terminal).

Using Tip

Note: tip is available in SFU  and Solaris as well as HP-UX and AIX. It uses configuration file /etc/remote. Connect the appropriate serial cable from serial port on laptop (usually serial port 1) to serial port A or SER MGT on target Sun system.

Use "tip hardwire" (not "hardware") to open a connection to the headless box before booting it: From a Solaris shell prompt on the local system, issue the command:

tip hardwire


tip ser1


hardwire is defined on Solaris in the /etc/remote to use port B (for laptop you need to correct this or add another line, see below):

dialup1|Dial-up system:\


If you need to connect from serial port A you need to modify this entry in /etc/remote or better add another entry, for example ser1


After tip session established you can boot the server. This tip session should be kept active as long as server remains online.

You should be connected. Press enter a few times to see if you are getting a response. If you are not, check your connections and make sure you have the right cable.

From within tip, you can access a tip menu by pressing ~? after a carriage return. To quit the tip session, press ~. and to send a break character, type ~#

To send a break character, type ~#

The hardwire parameter in the tip command refers to an entry in the file /etc/remote which describes the serial port connections. By default, hardwire specifies port B with 9600 baud, 8 data bits, no stop bits, and 1 parity bit. Connect, via a null modem, serial port "A" of the Sun to your terminal's serial port. Your terminal settings should be 9600 8N1, which are the default serial settings of the Sun.

If you use tip, if possible, emulate a SUNTERM

Using putty

PuTTY is a free and open source gui X based terminal emulator client for the SSH, Telnet, rlogin, and raw TCP computing protocols and as a serial console client. It works under Linux, Unix, Mac OS X, MS-Windows and few other operating systems. You just need to set port parameters and you are in business:

Using Teraterm

Using Teraterm is similar to using Putty. You just need to set correct parameters for serial port and you are in business

Using screen

This can be recommended only to heavy screen users who already know GNU screen very well. The first parameter to the screen command defines which type of window is created. If a tty name (e.g. "/dev/ttyS0") is specified as the first parameter to the screen command, then the window is directly connected to this device. An optional parameter is allowed consisting of a comma separated list of flags in the notation as follows:
screen /dev/ttySX baud_rate,cs8|cs7,ixon|-ixon,ixoff|-ixoff,istrip|-istrip
  • /dev/ttySX: Linux serial port (e.g., /dev/ttyS0 [COM1] )
  • baud_rate: Usually 300, 1200, 9600 or 19200. This affects transmission as well as receive speed.
  • cs8 or cs7: Specify the transmission of eight (or seven) bits per byte.
  • ixon or -ixon: Enables (or disables) software flow-control (CTRL-S/CTRL-Q) for sending data.
  • ixoff or -ixoff: Enables (or disables) software flow-control for receiving data.
  • istrip or -istrip: Clear (or keep) the eight bit in each received byte.

In this example, I'm connecting to my Soekris based embedded router using /dev/ttyS0 with 19200 baud rate and cs8:
$ screen /dev/ttyS0 19200,cs8


Connecting Using UUCP

Another common application  for connecting to a serial console is UUCP. Most Linux and Unix distributions include the UUCP application. Start UUCP with the command "cu -l [device] -s [speed]", where [device] is the serial port you are using, such as ttyS0 (COM1) or ttyS1 (COM2), and [speed] is the speed of the serial console that you are connecting to.

Here is an example:


# cu -l /dev/ttyS0 -s 9600

You may need to hit enter before you see the login prompt. If you see a bunch of weird characters, then you probably specified the wrong speed.

To exit, just type "~.".


Behavior of the Sun Serial Console

Now, depending upon the machine you have, and the revision of your PROM, you'll either be greeted by a ">" prompt or an "ok" prompt. Machines that have everything configured properly and a working OS will of course, begin to boot by themselves rather than displaying a prompt.

If you want to stop the boot from happening so you can wipe out the OS to install something else (or just perform maintenance) or make changes to the NVRAM, then, before the OS starts to load from the HD, (essentially, right after it tells you the hardware Ethernet address, but before it says "boot device"), you need to send a "break" signal.

Once you've sent a break, as above, you'll be greeted by "OK" prompt (FORTH interpreter prompt).

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How to get to the OK prompt without Sun keyboard

The UNIX and Linux Forums

Hi all,

I have just replaced the HDD on a Ultra 5 Spark machine, now I need to reinstall Solaris 9.
The problem is: how do I get to the OK prompt without a Sun keyboard in order to boot from CD?

At moment when I power on the machine I get the following error:
Timeout Waiting for ARP/RARP Packet
Probably because it's trying to boof off the network.

What are you using to connect to the server?

If using a laptop on the serial connection of the server, Control Break should get you to the ok prompt - but only if break is allowed.

Solaris Forums - Ctrl-Break in Serial Console

Ctrl-Break in Serial Console
Author: KurtGuenther Posts: 5 Registered: 8/1/05
Nov 30, 2005 8:54 AM

I can't seem to get Ctrl-Break to work in a serial console. I'm using Linux minicom, and I've tried two different keyboards.

Any ideas? Is there a "~break" command?

Re: Ctrl-Break in Serial Console
Author: rajanikk Posts: 9 Registered: 12/23/05
Dec 23, 2005 10:08 AM (reply 2 of 3)
try putty, using it u can send ctrl-break to serial console using mouse. no need for keyboard.

Using Serial Consoles - (Solaris / Linux) by Jeff Hunter, Sr. Database Administrator

The following article documents some of the tips for connecting the serial port of a UNIX Server (Sun SPARC / Linux) to the serial port (console) of a Sun Server. This is often helpful and even necessary when performing routine administrative tasks or initiating critical and/or long running processes. Access to the serial console for many Sun servers is the only way to perform administrative tasks given these servers do not come with a frame buffer (i.e. video card).

There are times when I need to initiate a long running job but cannot remain connected to the network for the duration of its execution. In cases like this, I can connect to the serial console of the Sun server, initiate the job and disconnect. The job will remain running even when I drop my connection to the serial port. I can, at a later time, reconnect to the serial console to determine the results.

The first two sections of this article explain the applications (programs) used from a Sun SPARC server and then a Linux server for obtaining a serial console connection. The remainder of this article attempts to describe the details (cables, connections, adapters) of obtaining a serial console connection to/from different Sun SPARC servers.

Connect From Sun SPARC Serial Port
From a Sun machine, if you wanted to access the serial console of another computer (ie. Linux, Sun, etc.), you would use the tip command. The configuration file for tip is /etc/remote. In most cases, you will be concerned with the hardwire entry in this file. First, connect the two machines by their serial ports (null modem if required), and from the Sun SPARC (Solaris) machine, type the following at the command-line to connect to the serial console of the other machine (Solaris / Linux):
  # tip hardwire
Below is an example /etc/remote file from the Sun SPARC (Solaris) machine that contains the hardwire entry to go through serial port B (/dev/term/b). If you wanted to change this entry to go out through serial port A instead, change "/dev/term/b" to "/dev/term/a".
dialup1|Dial-up system:\
The attributes are:

dv      device to use for the tty
el      EOL marks (default is NULL)
du      make a call flag (dial up)
pn      phone numbers (@ =>'s search phones file; possibly taken from
                              PHONES environment variable)
at      ACU type
ie      input EOF marks (default is NULL)
oe      output EOF string (default is NULL)
cu      call unit (default is dv)
br      baud rate (defaults to 300)
fs      frame size (default is BUFSIZ) -- used in buffering writes
          on receive operations
tc      to continue a capability
Connect to a Sun Serial Console from Linux

Linux provides two methods (programs) that can be used to connect to a serial console of a Sun server.

Connecting Using minicom

The first application I'll talk about is "minicom". Most Linux distributions (i.e. Red Hat) already include minicom. If your particular distribution does not include minicom, you can download it from the following URL:

Once you have Minicom installed, start it up with the command "minicom". Press "Ctrl-A Z" to get to the main menu. Press "o" to configure minicom. Go to "Serial port setup" and make sure that you are set to the correct "Serial Device" and that the speed on line E matches the speed of the serial console you are connecting to. (In most cases with Sun, this is 9600.) Here are the settings I made when using my Serial A / COM1 port on my Linux box:

| A -    Serial Device      : /dev/ttyS0                                |
| B - Lockfile Location     : /var/lock                                 |
| C -   Callin Program      :                                           |
| D -  Callout Program      :                                           |
| E -    Bps/Par/Bits       : 9600 8N1                                  |
| F - Hardware Flow Control : Yes                                       |
| G - Software Flow Control : No                                        |
|                                                                       |
|    Change which setting?                                              |
After making all necessary changes, hit the ESC key to go back to the "configurations" menu. Now go to "Modem and dialing". Change the "Init string" to "~^M~". Save the settings (as dflt), and then restart Minicom. You should now see a login prompt.

Connecting Using UUCP

Another common application to use in Linux for connecting to a serial console is UUCP. Most Linux distributions include the UUCP application. Start UUCP with the command "cu -l [device] -s [speed]", where [device] is the serial port you are using, such as ttyS0 (COM1) or ttyS1 (COM2), and [speed] is the speed of the serial console that you are connecting to.

Here is an example:

# cu -l /dev/ttyS0 -s 9600
You may need to hit enter before you see the login prompt. If you see a bunch of weird characters, then you probably specified the wrong speed.

To exit, just type "~.".

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SunHELP Serial Port & Cable Pinouts

RJ45 - DB25 RS232 serial converter cable, RJ45 - DB9 serial cable: Below are pinouts for an RJ45 - DB25 RS232 serial converter cable, part number 530-2889-01 and a RJ45 - DB9 serial cable, part number 530-3100-01. (There is also an unknown part number which has the same pinout except that the RJ45 BODY (black) is wired to RS232 pin 1 GND.)

Note that these are wired DCE. If you use the supplied RJ45 to DB25 RS232 adapter, you get a null-modem cable, suitable for a terminal connection.

Machine            Sun serial DB25              Machine            DB9 adapter
RJ45               RS-232 adapter               RJ45               RS-232 Pin
Pin                part # 530-2889-01           Pin                part # 530-3100-xx
1 (RTS) blue   — 5  (CTS)                     1 (RTS) blue   — 8 (CTS)
2 (DTR) orange — 6  (DSR)                     2 (DTR) orange — 6 (DSR)
3 (TXD) black  — 3  (RXD)                     3 (TXD) black  — 2 (RXD)
4 (GND) red    — 7  (GND)                     4 (GND) red    — 5 (GND)  
5 (GND) green  — 7  (GND)                     5 (GND) green  — 5 (GND)
6 (RXD) yellow — 2  (TXD)                     6 (RXD) yellow — 3 (TXD)
7 (DSR) brown  — 20 (DTR)                     7 (DSR) brown  — 4 (DTR)
8 (CTS) gray   — 4  (RTS)                     8 (CTS) gray   — 7 (RTS)


How To: Build a Null-Modem Serial Cable

Connect Pin to Pin on each end.
 25-pin 25-pin 2 --------------- 3 3 --------------- 2 4 --------------- 5 5 --------------- 4 7 --------------- 7 6 ---+ +----------- 20 8 ---+ +--- 6 20 ----------+ +--- 8 

This is the traditional "full handshaking" null modem cable. Adapters wired like this are available in most of the computer stores I've been in.

Now, if you want to convert straight to a 9pin connector Greg LeBlanc offers the following insight: "You need to have full duplex, otherwise, you just get output, but no return. (or, if you reverse the cable, you see nothing and can't tell that your keystrokes are going through.) simply checking three pins with a multimeter isn't cutting it. you need the following connections to have a fully compliant cable...

25 pin 9 pin pin 1 GND - pin 1 GND pin 2 TXD - pin 3 RXD pin 3 RXD - pin 3 TXD pin 4 RTS - pin 8 CTS pin 5 CTS - pin 7 RTS pin 7 gnd - pin 5 gnd pin 6 DSR - pin 4 DTR pin 20 DTR - pin 6 DSR 
Note that GND is frame ground and 'gnd' is Signal ground and the two should not be tied together...

Some Null modem cables tie 6/20 together on the 25 pin side, this doesn't always work with all equipment.

I included the 9-25 pin arrangement because most PCs use 9 pin mouse ports as the serial port, and most Sun's use real 25 pin serial connections

Null Modem

Null Modem Cable Wiring Diagram

RS232 serial null modem cable wiring and tutorial


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