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Connecting to Linux console

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Connecting to Linux console

Linux host PC

Prerequisites

  • PC with Ubuntu 16.04 operating system and USB port (for USB-UART converter connection) or local network connection (for SSH connection)
  • VisionCB-STD board with VisionSOM-6ULL and Linux image installed
  • Micro-USB cable

Connecting to Linux console through UART-USB converter

VisionCB-STD has built-in UART-USB converter, it lets you connect to the console via virtual COM port. First of all you need to determine what is the VisionCB-STD virtual COM number on your Linux system. To do that connect VisionCB-STD board to your PC with micro-USB cable and list your terminal devices: 

ls /dev/ttyUSB*
/dev/ttyUSB0

If there is only one device then it is the terminal you are looking for (/dev/ttyUSB0 in the example above), if there are more /dev/ttyUSB* terminal then disconnect and reconnect your board to find proper one.

Now install minicom: 

sudo apt install minicom

Start minicom: 

sudo minicom -b 115200 -D /dev/ttyUSB0 -s

Enter Serial port setup, press F to disable hardware flow control, press Enter, choose Exit, now you can log in. It is strongly recommended to change the default passwords of existing users. To do that enter passwd <user_name> command, you will be prompted to enter password twice: 

root@somlabs:~# passwd root
Enter new UNIX password:
Retype new UNIX password:
passwd: password updated successfully
root@somlabs:~#

To exit minicom press Ctrl+A, Z, X, then confirm by pressing Enter.

Connecting to Linux console via SSH client

Connecting as root - not recommended

Login to the UART-USB console as described in the previous section and change the root password. Once you have changed it (still via UART-USB connection) you need to modify /etc/ssh/sshd_config file: 

nano /etc/ssh/sshd_config

Add line: 

PermitRootLogin yes

Restart SSH service: 

service sshd restart

Now you can log in as root via SSH, you only need IP address of VisionSOM-6ULL. Enter ip a for list of all network interfaces and their IP addresses: 

root@somlabs:~# ip a
1: lo: <LOOPBACK,UP,LOWER_UP> mtu 65536 qdisc noqueue state UNKNOWN group default
    link/loopback 00:00:00:00:00:00 brd 00:00:00:00:00:00
    inet 127.0.0.1/8 scope host lo
       valid_lft forever preferred_lft forever
    inet6 ::1/128 scope host
       valid_lft forever preferred_lft forever
2: eth0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc pfifo_fast state UP group default qlen 1000
    link/ether a6:e3:1c:a0:3d:b0 brd ff:ff:ff:ff:ff:ff
    inet 192.168.0.25/24 brd 192.168.0.255 scope global eth0
       valid_lft forever preferred_lft forever
    inet6 2a02:a310:813c:d700:a4e3:1cff:fea0:3db0/64 scope global mngtmpaddr dynamic
       valid_lft 974055sec preferred_lft 369255sec
    inet6 fe80::a4e3:1cff:fea0:3db0/64 scope link
       valid_lft forever preferred_lft forever
3: sit0@NONE: <NOARP> mtu 1480 qdisc noop state DOWN group default
    link/sit 0.0.0.0 brd 0.0.0.0

In this case the IP address of the Ethernet (eth0) interface is 192.168.0.25. Now you can connect to VisionSOM-6ULL with SSH client from your Linux host PC: 

ssh root@192.168.0.25

Connecting as regular user

To connect as a regular user you need to create new account or use existing one. In the first case login as root through USB-UART converter or SSH, and add a new account and set password: 

root@somlabs:~# useradd tom
root@somlabs:~# passwd tom
Enter new UNIX password:
Retype new UNIX password:
passwd: password updated successfully
root@somlabs:~#

By default new user has no home directory and his shell is /bin/sh. To create home directory enter: 

root@somlabs:~# mkdir /home/tom

To change shell to bash enter: 

root@somlabs:~# chsh -s /bin/bash tom


Now you can log in as tom with SSH client.

Windows host PC

Prerequisites

  • PC with Windows operating system and USB port (for USB-UART converter connection) or local network connection (for SSH connection)
  • VisionCB-STD board with VisionSOM-6ULL and Linux image installed
  • Micro-USB cable
  • PuTTY terminal

Connecting to Linux console through UART-USB converter

VisionCB-STD has built-in UART-USB converter, it lets you connect to Linux console via virtual COM port. First of all you need to determine what is the VisionCB-STD virtual COM number on your Windows system, to do that open Control Panel, connect VisionCB-STD to your computer, find Ports (COM & LPT) and expand it. You should see USB Serial Port (COM<port_number>), if there is only one item with this name then it is your port, if there are more ports then disconnect and reconnect VisionCB-STD to check which port shows up. Now we can connect with PuTTY to your VisionSOM-6ULL, connect VisionCB-STD to your PC, run PuTTY and:

  • Select Serial in Connection type section
  • Enter VisionCB-STD port number in Serial line field
  • Enter 115200 in Speed field
  • Click Open

Now you can log in using one of existing user names. It is strongly recommended to change the default passwords of existing users. To do that enter passwd <user_name> command, you will be prompted to enter password twice: 

root@somlabs:~# passwd root
Enter new UNIX password:
Retype new UNIX password:
passwd: password updated successfully
root@somlabs:~#

Connecting to Linux console via SSH client

Connecting as root - not recommended

Login to the UART-USB console as described in the previous section and change the root password. Once you have changed it (still via UART-USB connection) you need to modify /etc/ssh/sshd_config file: 

nano /etc/ssh/sshd_config

Add line: 

PermitRootLogin yes

Restart SSH service: 

service sshd restart

Now you can log in as root via SSH, you only need IP address of VisionSOM-6ULL. Enter ip a for list of all network interfaces and their IP addresses: 

root@somlabs:~# ip a
1: lo: <LOOPBACK,UP,LOWER_UP> mtu 65536 qdisc noqueue state UNKNOWN group default
    link/loopback 00:00:00:00:00:00 brd 00:00:00:00:00:00
    inet 127.0.0.1/8 scope host lo
       valid_lft forever preferred_lft forever
    inet6 ::1/128 scope host
       valid_lft forever preferred_lft forever
2: eth0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc pfifo_fast state UP group default qlen 1000
    link/ether a6:e3:1c:a0:3d:b0 brd ff:ff:ff:ff:ff:ff
    inet 192.168.0.25/24 brd 192.168.0.255 scope global eth0
       valid_lft forever preferred_lft forever
    inet6 2a02:a310:813c:d700:a4e3:1cff:fea0:3db0/64 scope global mngtmpaddr dynamic
       valid_lft 974055sec preferred_lft 369255sec
    inet6 fe80::a4e3:1cff:fea0:3db0/64 scope link
       valid_lft forever preferred_lft forever
3: sit0@NONE: <NOARP> mtu 1480 qdisc noop state DOWN group default
    link/sit 0.0.0.0 brd 0.0.0.0

In this case the IP address of the Ethernet (eth0) interface is 192.168.0.25. Now you can connect to VisionSOM-6ULL with SSH client from your Windows host PC:

  • Start PuTTY
  • Enter VisionSOM-6ULL IP address in Host Name field
  • Click Open button
PuTTY connection window

Connecting as regular user

To connect as a regular user you need to create new account or use existing one. In the first case login as root through USB-UART converter or SSH, and add a new account and set password: 

root@somlabs:~# useradd tom
root@somlabs:~# passwd tom
Enter new UNIX password:
Retype new UNIX password:
passwd: password updated successfully
root@somlabs:~#

By default new user has no home directory and his shell is /bin/sh. To create home directory enter: 

root@somlabs:~# mkdir /home/tom

To change shell to bash enter: 

root@somlabs:~# chsh -s /bin/bash tom


Now you can log in as tom with SSH client.

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