SSH bastion is a jump server (or gateway server) that gives access to databases within a private network using the SSH protocol.

How to connect via SSH Tunnel

When setting up a connector, choose to Connect via SSH Tunnel.
Copy the unique SSH Public Key
Setup a Streamkap user on your bastion host
Add the ssh-ed25519 key to the streamkap user on the bastion host
Add Streamkap IP Addresses to your allowed hosts.
Input bastion address into SSH Host
Input the username into SSH User

Why ssh-ed25519 keys vs RSA?

The Ed25519 algorithm has superior security characteristics and computational efficiency.

Robust Security: The Ed25519 algorithm is based on elliptic curve cryptography (ECC), providing a high level of security with a 128-bit security level. It offers strong resistance against brute force attacks, making it highly suitable for protecting your remote access credentials.
Smaller Key Size: Ed25519 keys are smaller than their RSA counterparts, reducing the storage and transmission overhead. Smaller keys also contribute to faster authentication times, improving overall connection speeds.
Fast Key Generation: Generating Ed25519 keys is faster compared to traditional RSA keys

How to Setup a Bastion Host

Setup Linux SSH Host

-- Create group streamkap:
sudo groupadd streamkap  

  -- Create user streamkap:
sudo useradd -m -g streamkap streamkap  

-- Switch to the Streamkap user:
sudo su - streamkap  
 
-- Create the .ssh directory:
mkdir ~/.ssh  
-- Set permissions:
chmod 700 ~/.ssh  

-- Change to the .ssh directory:
cd ~/.ssh  

  --Create the authorized_keys file:
touch authorized_keys  

-- Set permissions:
chmod 600 authorized_keys  

-- Using the key given to you from Streamkap, add this to the authorized_keys file.
echo "<key>" >> ~/.ssh/authorized_keys

Once the user is created, you'll need to allow IP and port access in these two locations

Streamkap IP to your tunnel server's SSH port. See Streamkap IP Addresses
Your SSH tunnel server to your connector IP and Port

Setup Windows SSH Host

  -- Create user streamkap:

net user streamkap <password> /add /comment:"Streamkap User" /passwordchg:no /passwordreq:no /logonpasswordchg:no  

-- Create group streamkap:

net localgroup streamkap-group /comment:"Streamkap Group" /add  

-- In Windows command prompt, switch to the SSH server directory.

cd C:\\ProgramData\\ssh\\ && start notepad .\\sshd_config  

-- Allow password authentication for the Streamkap user.

PasswordAuthentication yes  

-- Allow the Streamkap user to connect to the SSH server. Add the following line to the sshd_config file.

AllowUsers streamkap

-- If your Windows build is 1809 or later, comment out the following lines in the sshd_config file:
# Match Group administrators
# AuthorizedKeysFile **PROGRAMDATA**/ssh/administrators_authorized_keys

Save the sshd_config file.

-- Restart the agent and the sshd service. If the following command fails, you can restart from the Task Manager (Alt + Ctrl + Delete).

Restart-Service ssh-agent; Restart-Service sshd

-- Go into the SSH server using Windows VM.
ssh streamkap@<DNS Name>

  -- Create an .ssh folder in your home directory.
mkdir .ssh

- Add an authorized_keys file if it does not exist
-- If your client is Windows PowerShell:

type nul > authorized_keys  
echo <streamkap-public-key> >> authorized_keys  
icacls C:\\Users\\streamkap\.ssh\\authorized_keys /inheritance:r  

-- If your client is Linux:

touch authorized_keys  
chmod 600 authorized_keys  
echo <streamkap-public-key> >> authorized_keys

If you're running PowerShell in elevated mode, your setup is complete.

If you're not running PowerShell in elevated mode, follow the instructions below.

-- Allow public key authentication
PubkeyAuthentication yes

-- Remove password authentication.
PasswordAuthentication no  
PermitEmptyPasswords no

Save the sshd_config file.

Verify that inheritance has been disabled and remove Administrator.

Right click on the authorized_keys file
Select Properties
Select the Security tab
Select Advanced
Verify that the bottom left reads Enable Inheritance, which means that inheritance is disabled
Remove Administrator from the file security permissions.

Restart the agent and the sshd service.

Restart-Service ssh-agent; Restart-Service sshd