Docker container with SSHD running in Ubuntu

This repository contains a Docker image definition that can be used to run SSHD server in Ubuntu. A pair of private/public keys is automatically generated on startup, and the private key is sent to stdout. This can be useful if you need to run a temporary container and do not want to generate keys yourself, or have no way to add your public key to the container.

Another supported scenario is to pass the public key via environment variable PUBLIC_KEY. In this case the private key is not generated.

Usage

1. Run SSH server in Docker, generate the key pair automatically
2. Run SSH server in Docker, pass public key via environment variable
3. Use Docker image with common tools pre-installed
4. Run SSH server in Azure Container Instances (Azure CLI)
5. Run SSH server in Azure Container Instances (Terraform)

Run SSH server in Docker, generate the key pair automatically

docker run -it --rm -p 2222:22 andreygoran/sshd-ubuntu

The output will be like this:

-----BEGIN OPENSSH PRIVATE KEY-----
...private key goes here...
-----END OPENSSH PRIVATE KEY-----
Server listening on 0.0.0.0 port 22.
Server listening on :: port 22.

In this example we map SSH to port 2222, so to login we can use this code (replace 172.16.10.100 with the actual IP):

# Save private key to /tmp/key
touch /tmp/key && chmod 600 /tmp/key
cat > /tmp/key <<- "EOF"
-----BEGIN OPENSSH PRIVATE KEY-----
...private key goes here...
-----END OPENSSH PRIVATE KEY-----
EOF
# Login to the container via ssh using port 2222 and the private key in /tmp/key
ssh -p 2222 -i /tmp/key root@172.16.10.100

Run SSH server in Docker, pass public key via environment variable

docker run -it --rm -p 2222:22 -e PUBLIC_KEY="...public key goes here..." andreygoran/sshd-ubuntu

The output will be like this:

Server listening on 0.0.0.0 port 22.
Server listening on :: port 22.

In this example we map SSH to port 2222, so to login we can use this code (replace 172.16.10.100 with the actual IP):

ssh -p 2222 root@172.16.10.100

We are assuming that SSH has access to your private key on the system where you are running it.

Use Docker image with common tools pre-installed

The andreygoran/sshd-ubuntu image only comes with the openssh-server package installed on top of Ubuntu image. If you need an image with common tools pre-installed, use andreygoran/sshd-ubuntu-tools instead:

docker run -it --rm -p 2222:22 andreygoran/sshd-ubuntu-tools

or

docker run -it --rm -p 2222:22 -e PUBLIC_KEY="...public key goes here..." andreygoran/sshd-ubuntu-tools

Here is the list of packages included in andreygoran/sshd-ubuntu-tools:

• openssh-server
• openssh-client
• nano
• vim
• less
• curl
• wget
• jq
• net-tools
• iproute2
• netcat
• dnsutils
• iputils-ping
• iptables
• nmap
• tcpdump
• telnet

Run SSH server in Azure Container Instances (Azure CLI)

# Create resouce group
az group create --name sshd-resource-group --location eastus2 --output none

# Create container instance
az container create -g sshd-resource-group --name sshd --image andreygoran/sshd-ubuntu --ports 22 --ip-address Public --environment-variables PUBLIC_KEY="...public key goes here..." --query ipAddress.ip --output tsv

IP address will be shown in the az command output:

20.14.241.9

Connect via SSH (replace 20.14.241.9 with your own IP):

$ ssh -o StrictHostKeyChecking=no root@20.14.241.9
Warning: Permanently added '20.14.241.9' (ED25519) to the list of known hosts.
Welcome to Ubuntu 22.04.2 LTS (GNU/Linux 5.10.102.2-microsoft-standard x86_64)

 * Documentation:  https://help.ubuntu.com
 * Management:     https://landscape.canonical.com
 * Support:        https://ubuntu.com/advantage

This system has been minimized by removing packages and content that are
not required on a system that users do not log into.

To restore this content, you can run the 'unminimize' command.

The programs included with the Ubuntu system are free software;
the exact distribution terms for each program are described in the
individual files in /usr/share/doc/*/copyright.

Ubuntu comes with ABSOLUTELY NO WARRANTY, to the extent permitted by
applicable law.

root@SandboxHost-638271063068646531:~#

or run remote command via SSH:

$ ssh -o StrictHostKeyChecking=no root@20.14.246.40 "cat /etc/issue"
Ubuntu 22.04.2 LTS \n \l

$

Run SSH server in Azure Container Instances (Terraform)

Terraform can be used to run SSH server in Azure Container Instances.

Run with public key passed via Terraform variable

See terraform configuration

Run with public/private keys generated by Terraform

See terraform configuration