Local connection between 2 computers

The last modifications of this post were around 1 year ago, some information may be outdated!

Scenario: I wanna control / access my comp1 (which runs Linux) from my comp2 (which runs MacOS).
Reason: I cannot work with Data Science's stuff with comp2 (Mac M1) whereas comp1 has everything (Linux, GPU,...)

Two computers must be connected to the same network!

👉 Note: SSH.
👉 Note: Docker + GPUs
👉 Note: Docker 101

Control visually

I use NoMachine (I think it's faster and more controllable than TeamViewer).

Connect to a NoMachine Server running on Windows

It requires username and password and you are connected using your Microsoft account, don't user the username and password being set up in the System Preferences, use your Microsoft Account credentials!

Connect via SSH

👉 I learned from this answer.

❇️ On the "server computer" (comp1 -- Linux)

# Knowing its name
hostname
# or `hostnamectl` or `cat /proc/sys/kernel/hostname`
# mine: pop-os

# Knowing current user
whoami
# mine: thi
# You must know the password!!!

# Install openssh-server
sudo apt update
sudo apt install openssh-server

# Check comp1's ip
ifconfig | grep "192.168"
# mine: 192.168.1.115

Test: connect from comp1 to comp1 itself!

ssh 127.0.0.1
# type user1's password

❇️ On the "client computer" (comp2 -- MacOS)

# Connect via comp1's name
ssh [email protected]
# Type thi's password

# Connect via comp1's ip
ssh [email protected]

❇️ Disconnect

exit

❇️ Copy files

# From client to remote
scp /from/client/file.zip [email protected]:/on/remote/
# (change the destination name)
scp /on/client/file.zip [email protected]:/on/remote/file_renamed.zip

# From remote to client
scp [email protected]:/on/remote/file.zip /on/client/

Tip: You can use a smtp client (eg: CyberDuck) to make things visually

# server
pop-os.local # or using ip address
# port
22
# username
thi
# password

Open Jupter Notebook running on comp1

👉 Note: Docker
👉 Note: SSH

Suppose that there is a jupyter lab server which is running on comp1 (In my case, it's running inside a docker container which is ported to comp1 via port 8888).

# On comp2
ssh -N -L localhost:8888:127.0.0.1:8888 [email protected]
# Remark: keep the terminal

Then open http://localhost:8888/lab to see the result!

SSH to the docker container inside comp1

I wanna ssh to the container which is running on comp1 from comp2.

❇️ Suppose that the running container on comp1 is created from an image which hasn't set up the open-ssh by default. We will set up a server in the running container,

# Check the name of running container
docker ps # mine: docker_ai

# Go inside the running container
docker exec -it docker_ai bash

# [in the container]

# Install ssh server
apt update && apt install openssh-server && apt install nano
# Change `root`'s password
passwd # suppose: qwerty

nano /etc/ssh/sshd_config
# and add
Port 2222
PermitRootLogin yes

# Restart ssh server
/etc/init.d/ssh start

In the docker-compose.yml

# expose the ports
ports:
	- "6789:2222"

# Test on comp1
ssh -p 6789 root@localhost
# enter "qwerty" password for "root"

# Connect from comp2
ssh -p 6789 [email protected]
# enter "qwerty" password for "root"

❇️ In case your image has already installed openssh-server but forgot to run it by default. We will run the ssh server on port 22 for the running container.

RUN apt-get install -y openssh-server
RUN mkdir /var/run/sshd
RUN echo 'root:qwerty' | chpasswd
RUN sed -i 's/#PermitRootLogin prohibit-password/PermitRootLogin yes/' /etc/ssh/sshd_config
# SSH login fix. Otherwise user is kicked off after login
RUN sed 's@session\s*required\s*pam_loginuid.so@session optional pam_loginuid.so@g' -i /etc/pam.d/sshd
# need?
ENV NOTVISIBLE "in users profile"
RUN echo "export VISIBLE=now" >> /etc/profile
# Export port ssh
EXPOSE 22

Add below line to Dockerfile if you wanna run the openssh-server by default

CMD $(which sshd) -Ddp 22

We shouldn't (cannot??) run 2 servers in parallel in the docker image (for example, one for jupyter notebook on port 8888 and one for openssh-server on port 22).

💡 In this case, you should keep the jupyter notebook running. Each time you wanna run the openssh-server, you can run

docker exec docker_ai $(which sshd) -Ddp 22 # and keep this tab open
# or
docker exec -d .... # detach mode

You can also do this completely from comp2,

ssh [email protected]
# Then you are in comp1's terminal
docker exec ....

Important remark: If you enter the container's shell and then you wanna exit with exit or logout command. It also terminates the server and you have to run the server again!

Don't forget to forward the port 22 (in container) to 6789 in comp1 via docker-compose.yml.

# On comp1
docker exec <container_name> $(which sshd) -Ddp 22
# Keep this tab open and running

# On comp2
ssh -p 6789 [email protected]
# enter pwd: "qwerty" as in the Dockerfile