I previously posted a guide on how to use OCI Bastion to connect to a Windows VM using RDP, I’ve also been playing around with connecting to Linux VMs via OCI Bastion using SSH.
As Bastion sessions have a maximum session TTL of 3 hours this means that in a given day I’d need to go through the process of creating a new Bastion session multiple times if I needed continued access to the VM. As I’m lazy, I’ve put together a Python script that automates Bastion session creation for Managed SSH sessions which does the following:
- Checks the active sessions on a given OCI Bastion 🔍
- If there isn’t an active session for the specified server, create a new managed SSH sessions and return the SSH command to connect (copies to the clipboard)
- If there is an active session, simply return the SSH command to connect (copies to the clipboard)
When the script has run, the SSH command to connect to the VM is in the clipboard so simply paste this into a terminal to connect.
The script is a little rough around the edges but it get’s the job done, I’ll likely optimise it over time – including making it easier to connect to multiple servers via multiple Bastions.
To run the script you’ll need the following information:
- OCID of the Bastion to use ✅
- OCID of the server (VM) to connect to ✅
- The path to the private key used for Bastion and SSH authentication ✅
- The contents of the associated public key ✅
The script can be found below and is also available on GitHub.
# This script queries the active sessions on a given OCI bastion (bastionocid), if it doesn't find a session for the specified server (serverocid)
# it will create a new bastion session and returns the resultant SSH command to connect to the server and copies to the clipboard, simply paste this into a terminal to connect,
# if their is an active session for the server, it returns the SSH command to connect to the server and copies to the clipboard, simply paste into a terminal to connect
# pip install oci - if you don't have this installed
import oci
# pip install pyperclip - if you don't have this installed
import pyperclip
import json
import time
# OCID of the bastion to query
bastionocid = "BASTIONOCID"
# OCID of the server to connect to
server = "SERVEROCID"
# Private key
privatekeypath = "D:\\OCI\\OCI.key" # Update to the correct location of the private key, this script was developed on Windows, hence the double slashes.
# Public key used for auth to bastion (using the same key for the VM too, to make it simple)
publickey = "PUBLICKEY" # Copy/paste the content of the public key file (.pub)
# Read the config
config = oci.config.from_file()
# Create client with the default config file (\.oci\config)
bastionclient = oci.bastion.BastionClient(config)
# List the current sessions
bastionsessions = bastionclient.list_sessions(bastion_id = bastionocid)
sessionsJSON = json.loads(str((bastionsessions.data)))
# See if there is an active session for the server, if there isn't create one
for session in sessionsJSON:
if session["lifecycle_state"] == "ACTIVE" and session["target_resource_details"]["target_resource_id"] == server:
print("Active Session Found : " + session["display_name"])
# Get the session and return the ssh command generated
getsession = bastionclient.get_session(session_id = session["id"])
sshcmd = getsession.data.ssh_metadata["command"]
# Automate connecting - replace the placeholder for private key with the correct location
sshcmd = sshcmd.replace("<privateKey>",privatekeypath)
# Copy the SSH command to the clipboard so that it can be pasted into PowerShell
pyperclip.copy(sshcmd)
break
else:
print("No active session found - creating a session.....")
create_session_response = bastionclient.create_session(
create_session_details=oci.bastion.models.CreateSessionDetails(
bastion_id=bastionocid,target_resource_details=oci.bastion.models.CreateManagedSshSessionTargetResourceDetails(
session_type="MANAGED_SSH",target_resource_id=server,target_resource_operating_system_user_name="opc"),
key_details=oci.bastion.models.PublicKeyDetails(public_key_content=publickey),session_ttl_in_seconds = 10800,
))
# Get the session and return the ssh command generated
time.sleep(120)
session = bastionclient.get_session(session_id = create_session_response.data.id)
sshcmd = session.data.ssh_metadata["command"]
# Automate connecting - replace the placeholder for private key with the correct location
sshcmd = sshcmd.replace("<privateKey>",privatekeypath)
# Copy the SSH command to the clipboard so that it can be pasted into PowerShell
pyperclip.copy(sshcmd)
print("Session created, paste the resultant SSH command from the clipboard")
break
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