On Windows, COM ports are named COM1 through COM256. On Linux, serial devices can have arbitrary names but are typically character devices with a major number of 4 and a minor number from 64 to 256 represented by /dev/ttyS0 through /dev/ttyS191. By default init will populate this mapping using the mknod system call. One additional step for Ubuntu, is to enable getty(8) for serial console by your own. Ubuntu uses upstart init system, we need to create a file called /etc/init/ttyS0.conf containing the following: # ttyS0 - getty # # This service maintains a getty on ttyS0 from the point the system is # started until it is shut down again. Enable serial console on Ubuntu 16.04.1 on ARM64. TIME Timed out waiting for device dev-ttyMV0.device. DEPEND Dependency failed for Serial Getty on ttyMV0. I tried various systemd settings and followed instructions from here (1) and here (2), without success. In Ubuntu 14.04 I used the /etc/init/ttyS0.conf, but this is not valid anymore.
One caveat is that the grub serial console portion does not function since this is a USB port and the driver is not loaded until the kernel boots. For my installation, I am running the following: CentOS Linux 7.1.1503 (Core) x8664 Minimal install efi partition Setup tty0 console and ttyUSB0 serial console: Since this is a CentOS efi partitioned system, the grub.cfg file that is used during boot is. Login prompt to serial console is as below. 4.1 Single user mode / Recovery mode. When running single user mode, there will be two root prompt for tty1 and ttyS0. When running recovery mode, there will be one root prompt for ttyS0. How to enable USB-Serial Port adapter (RS-232) in Ubuntu Linux. Here’s how to enable USB-Serial port adapter in Ubuntu Linux (with credit to Freeman from RepRap forum) First plug in the USB-Serial Port adaptor to one of your USB port. Wait for a couple of second, then run “dmesg”. You should see these message at the end of dmesg output.
Using a serial console on Linux is much like using a modem; the technology is virtually identical, but instead of using a modem to dial into a remote system, a special serial cable, called a null-modem cable, is strung between two computers via their serial ports. Most modern desktops and laptops no longer come with serial ports; however, virtually all server-class systems do. Install incredimail on windows 10.
The one system is set up to listen on one end of the cable, and the other system is used to log in, as the client, on the other end. This can be reverted very easily; a null-modem cable works both ways. Why use a serial console? For one, it can be very useful for debugging, particularly if the network is down and the system is headless. For another, you can use it to bypass security rules and bridge one network to another -- not for things like copying files, but purely for login purposes to obtain shell access to the other system. For instance, if you had a server in a DMZ, you could bypass potentially complex networking needs to obtain shell access to the server from a system on the LAN. This also could mean that running a remotely-accessible sshd service is no longer required on the DMZ server.
Free text editors. To begin, all you really need is the null-modem cable and two systems with serial ports, making sure the serial ports are enabled in the BIOS. On the server, edit /etc/inittab and add:
This tells init to launch agetty, listening on /dev/ttyS0 (the first serial port) at a baud-rate of 115200bps, and to use vt102 terminal emulation. On the client, once the null-modem cable is in place and agetty is running, use screen to connect:
Hit enter once screen starts and you will be sitting at a familiar login prompt on the remote system. To disconnect, simply type [CTRL-A]+K in screen, after logging out.
If you were so inclined, you could also force syslog to send all logs to the serial port as well, for observation over the serial line. This can be done by modifying /etc/syslog.conf to add:
If nothing else, should you need to connect to some hardware via the console, like a network router or switch, being able to use screen to manage the serial connection is a great and easy way to do so. Virtually all Linux distributions either come with screen preinstalled, or it's a simple apt-get, urpmi, or yum away. Most Linux distributions come with agetty already installed.
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Active1 year, 5 months ago
How can I enable remote terminal log in into Ubuntu 9.10 (Karmic Koala) using a USB serial port?
Linux Serial Console
I created device /dev/ttyUSB0, and I want to allow logins using HyperTerminal.
I found some resources, but they are related to real hardware RS-232 ports. I can't find any information about a USB converter.
So far I have established connection between that USB-serial port and my laptop. I can send text to the port (cp sometext.txt /dev/ttyUSB0) and read it using HyperTerminal.
What do I need to do to enable logins on this port?
migrated from stackoverflow.comMar 21 '10 at 14:23
This question came from our site for professional and enthusiast programmers.
2 Answers
Ubuntu Serial Tool
See the Ubuntu Serial Console HowTo. You'll need to adapt it for your hardware -- instead of ttyS0, which is the first hardware serial port, you'll need to use ttyUSB0. An example of this is below.
At minimum, you need to configure upstart to start a getty on that port.
Create /etc/init/ttyUSB0.conf and paste the following into it:
Start the getty:
Older Ubuntu versions and distributions that don't use upstart do this by adding a line in /etc/inittab.
Linux Connect To Serial Console
This doesn't consider changes to the bootloader configuration to allow Grub to talk to the serial port; refer to the HowTo for details. I'm not sure if Grub can talk to a USB serial port or if that's limited to hardware ports.