Firefox

Purpose: Sometimes you just want an instance of Firefox running on an Alpine Linux container, that has persistence (Extensions, bookmarks, history, etc) outside of the container (with bind-mapped folders). This is useful for a number of reasons, but insecure by default, so you have to protect it behind something like a Keycloak Server so it is not misused.

Keycloak Authentication Sequence¶

sequenceDiagram
    participant User
    participant Traefik as Traefik Reverse Proxy
    participant Keycloak
    participant RockyLinux as Rocky Linux VM
    participant FirewallD as FirewallD
    participant Alpine as Alpine Container

    User->>Traefik: Access https://work-environment.bunny-lab.io
    Traefik->>Keycloak: Redirect to Authenticate against Work Realm
    User->>Keycloak: Authenticate
    Keycloak->>User: Authorization Cookie Stored on Internet Browser
    User->>Traefik: Pass Authorization Cookie to Traefik
    Traefik->>RockyLinux: Traefik Forwards Traffic to Rocky Linux VM
    RockyLinux->>FirewallD: Traffic Passes Local Firewall
    FirewallD->>RockyLinux: Filter traffic (Port 5800)
    FirewallD->>Alpine: Allow Traffic from Traefik
    Alpine->>User: WebUI Access to Firefox Work Environment Granted

Docker Configuration¶

version: '3'
services:
  firefox:
    image: jlesage/firefox # Docker image for Firefox
    environment:
      - TZ=America/Denver # Timezone setting
      - DARK_MODE=1 # Enable dark mode
      - WEB_AUDIO=1 # Enable web audio
      - KEEP_APP_RUNNING=1 # Keep the application running
    ports:
      - "5800:5800" # Port mapping for VNC WebUI
    volumes:
      - /srv/containers/firefox:/config:rw # Persistent storage for configuration
    restart: always # Always restart the container in case of failure
    network_mode: host # Use the host network

N/A

Local Firewall Hardening¶

It is important, due to how this browser just allows anyone to access it, to lock it down to only allow access to the SSH port and port 5800 to specifically-allowed devices, in this case, the Traefik Reverse Proxy. This ensures that it only allows the proxy to communicate with Firefox's container, keeping it securely protected behind Keycloak's middware in Traefik.

These rules will drop all traffic by default, allow port 22, and restrict access to port 5800.

# Set the default zone to drop
sudo firewall-cmd --set-default-zone=drop

# Create a new zone named custom-trusted
sudo firewall-cmd --permanent --new-zone=traefik-proxy

# Allow traffic to port 5800 only from 192.168.5.29 in the traefik-proxy zone
sudo firewall-cmd --permanent --zone=traefik-proxy --add-source=192.168.5.29
sudo firewall-cmd --permanent --zone=traefik-proxy --add-port=5800/tcp

# Allow SSH traffic on port 22 from any IP in the drop zone
sudo firewall-cmd --permanent --zone=drop --add-service=ssh

# Reload FirewallD to apply the changes
sudo firewall-cmd --reload

Traefik Reverse Proxy Configuration¶

If the container does not run on the same host as Traefik, you will need to manually add configuration to Traefik's dynamic config file, outlined below.

http:
  routers:
    work-environment:
      entryPoints:
        - websecure
      tls:
        certResolver: letsencrypt
      service: work-environment
      rule: Host(`work-environment.bunny-lab.io`)
      middlewares:
        - work-environment  # Referencing the Keycloak Server

  services:
    work-environment:
      loadBalancer:
        servers:
          - url: http://192.168.5.4:5800
        passHostHeader: true
#        # Adding forwardingTimeouts to set the send and read timeouts to 1 hour (3600 seconds)
#        forwardingTimeouts:
#          dialTimeout: "3600s"
#          responseHeaderTimeout: "3600s"

Firefox Special Configurations¶

Due to the nature of how this is deployed, you need to make some additional configurations to the Firefox settings after-the-fact. Some of this could be automated with environment variables at deployment time, but for now will be handled manually.

• Install Power Tabs Extension: This extension is useful for keeping things organized.
• Install Merge All Windows Extension: At times, you may misclick somewhere in the Firefox environment causing Firefox to open a new instance / window losing all of your tabs, and because there is no window manager, there is no way to alt+tab or switch between the instances of Firefox, effectively breaking your current session forcing you to re-open tabs. With this extension, you can merge all of the windows, collapsing them into one window, resolving the issue.
• Configure New Tab behavior: If a new tab opens in a new window, it will absolutely throw everything into disarray, that is why all hyperlinks will be forced to open in a new tab instead of a new window. You can do this by navigating to about:config and setting the variable browser.link.open_newwindow.restriction to a value of 0. Original Reference Documentation