Reverse Proxy

About Reverse Proxies

While ZNC is a fantastic bouncer, in many situations it can be beneficial to utilize a reverse proxy in front of it for features such as:

• Subdomains
• Tighter control of SSL ciphers and protocols
• ECDH support
• SSL session caching
• SSL stapling
• Compression

Notes

• TrustedProxy must be set in your configuration for web access logs to reflect actual addresses instead of the reverse proxy address (127.0.0.1 / ::1):

TrustedProxy = 127.0.0.1
TrustedProxy = ::1

Nginx

Note: If you plan on utilizing Nginx for IRC in conjunction with HTTP/HTTPS, the port number (or address) of the two services must be different.

HTTP

As a Subdomain

server {
    listen      80;
    listen      [::]:80;
    # To listen on a specific address only:
    # listen      192.0.2.1:80;
    # listen      [2001:db8::192:0:2:1]:80;
    server_name znc.example.test;
    access_log  /var/log/nginx/znc.example.test/znc-access.log;
    error_log   /var/log/nginx/znc.example.test/znc-error.log;

    location / {
        proxy_pass http://[::1]:6667/;
        # For IPv4 loopback (there's almost no reason to do this)
        # proxy_pass http://127.0.0.1:6667/;
        proxy_set_header X-Forwarded-For $proxy_add_x_forwarded_for;
    }
}

As a Subdirectory

Note:

• There is intentionally no / after the port number
• You must set URIPrefix of the Listener in ZNC to the target location (/znc/ in this example)

server {
    ...
    location /znc/ {
        proxy_pass http://[::1]:6667;
        proxy_set_header X-Forwarded-For $proxy_add_x_forwarded_for;
    }
}

On most distributions this would be put in /etc/nginx/conf.d/znc.example.test.conf .

HTTPS

This is a basic configuration utilizing Diffie Hellman key exchange:

server {
    listen      7001 ssl http2;
    listen      [::]:7001 ssl http2;
    # To listen on a specific address only:
    # listen      192.0.2.1:7001 ssl http2;
    # listen      [2001:db8::192:0:2:1]:7001 ssl http2;
    server_name znc.example.test;
    access_log  /var/log/nginx/znc.example.test/znc_ssl-access.log;
    error_log   /var/log/nginx/znc.example.test/znc_ssl-error.log;

    # SSL options
    add_header              Strict-Transport-Security "max-age=31536000; includeSubDomains; preload" always;
    ssl_certificate         /etc/letsencrypt/live/znc.example.test/fullchain.pem;
    ssl_certificate_key     /etc/letsencrypt/live/znc.example.test/privkey.pem;
    ssl_dhparam             /etc/letsencrypt/live/znc.example.test/dhparam.pem;
    ssl_trusted_certificate /etc/letsencrypt/live/znc.example.test/chain.pem;

    location / {
        proxy_pass http://[::1]:7001$uri;
        # For IPv4 loopback (there's almost no reason to do this)
        # proxy_pass http://127.0.0.1:7001$uri;
        proxy_set_header X-Forwarded-For $proxy_add_x_forwarded_for;
    }
}

On most distributions this would be put in /etc/nginx/conf.d/znc.example.test.conf .

IRC

Nginx has a directive separate from http called stream for protocols other than HTTP. We can utilize this to allow nginx to act as a reverse proxy for ZNC:

upstream znc {
    server [::1]:7000;
    # For IPv4 loopback (there's almost no reason to do this)
    # server 127.0.0.1:7000;
}

server {

    listen      7000 ssl;
    listen      [::]:7000 ssl;
    # To listen on a specific address only:
    # listen      192.0.2.1:7000 ssl;
    # listen      [2001:db8::192:0:2:1]:7000 ssl;

    # SSL options
    ssl_certificate         /etc/letsencrypt/live/znc.example.test/fullchain.pem;
    ssl_certificate_key     /etc/letsencrypt/live/znc.example.test/privkey.pem;
    ssl_dhparam             /etc/letsencrypt/live/znc.example.test/dhparam.pem;
    ssl_trusted_certificate /etc/letsencrypt/live/znc.example.test/chain.pem;
    
    proxy_pass znc;
} 

On most distributions these would be put in /etc/nginx/conf.d/znc.example.test.stream .

Additional Configuration Abilities

Nginx has many configuration options that can enhance the behavior of both the ZNC web interface and IRC, so the http or server nginx directive options below only demonstrate the most common portions of them:

    sendfile            on;
    tcp_nopush          on;
    tcp_nodelay         on;
    keepalive_timeout   65;
    types_hash_max_size 2048;

    server_tokens off;

    # Compression
    gzip                on;
    gzip_comp_level     9;
    gzip_types          application/javascript application/vnd.ms-fontobject application/x-font-otf application/x-font-ttf application/x-font-woff image/jpg image/png image/svg image/x-icon text/css;

    ###############
    # SSL options #
    ###############
    ssl_ciphers                 ECDHE-RSA-AES256-GCM-SHA384:ECDHE-RSA-AES256-SHA384:ECDHE-ECDSA-AES256-GCM-SHA384:ECDHE-ECDSA-AES256-SHA384:DHE-DSS-AES256-GCM-SHA384:DHE-DSS-AES256-SHA256:DHE-RSA-AES256-GCM-SHA384:DHE-RSA-AES256-SHA256;
    ssl_ecdh_curve              secp384r1;
    ssl_protocols               TLSv1.2 TLSv1.3;
    ssl_prefer_server_ciphers   on;
    ssl_session_cache           shared:https:15m;
    ssl_session_timeout         15m;

    # Stapling
    ssl_stapling                on;
    ssl_stapling_verify         on;
    resolver                    1.1.1.1 8.8.8.8 [2606:4700:4700::1111] [2001:4860:4860::8888];

lighttpd

HTTP

$HTTP["host"] =~ "^(sub\.domain\.com)$" {
  proxy.server = ( "" => ( ( "host" => "127.0.0.1", "port" => 6667 ) ) )
}

Traefik

It is possible to run ZNC as a docker container, and use Traefik to provide proxying services for this. The IRC port needs to be separated from the web interface port to achieve this.

Traefik setup

Traefik needs to be configured to listen on a specific port for IRC access to ZNC. In this example, I'm using port 7000 for 'web' based access, and 7001 for 'IRC' access. This can be done in docker-compose as follows:

version: "3.5"
networks:
  default:
    name: traefik

services:
  traefik:
    image: "traefik:v2.3"
    command:
        --entryPoints.web.address=:7000
        --entryPoints.irc.address=:7001
        --providers.docker=true
    ports:
      - "7000:7000"
      - "7001:7001"

ZNC setup

ZNC also needs to be configured to allow a separate port for IRC access. In this example, I'm using port 6501 for web access, and 6502 for IRC access. This is configured as follows:

ZNC Port Configuration

The ZNC docker container then needs to be configured with appropriate labels to configure traefik to send traffic to it. This can be done in docker-compose as follows (in this case, the host name 'znc.example.com' is being used to access the ZNC service):

---
version: "3.5"

networks:
  traefik:
    external: true

  default:
    name: znc

services:
  znc:
    image: znc
    container_name: znc
    volumes:
      - ./zncconfig:/znc-data
    networks:
      - default
      - traefik
    ports:
      - 6501:6501
      - 6502:6502
    restart: unless-stopped
    labels:
      - "traefik.enable=true"
      - "traefik.http.routers.zncweb.rule=Host(`znc.example.com`)"
      - "traefik.http.routers.zncweb.tls=true"
      - "traefik.http.routers.zncweb.entryPoints=web"
      - "traefik.http.services.zncweb.loadbalancer.server.port=6501"
      - "traefik.tcp.routers.zncirc.rule=HostSNI(`znc.example.com`)"
      - "traefik.tcp.routers.zncirc.tls=true"
      - "traefik.tcp.routers.zncirc.entryPoints=irc"
      - "traefik.tcp.services.zncirc.loadbalancer.server.port=6502"
      - "traefik.docker.network=traefik"

IRC client setup

All that is required then is to configure your IRC client to connect securely to 'znc.example.com' on port 7001, with SSL enabled. Traefik will then provide the appropriate certificate for the connection, and pass traffic to port 6502 on the ZNC container.

ZNC web control panel

The ZNC web control panel can be accessed using (in this case) https://znc.example.com:7000/

Caddy

Caddy is an extensible, cross-platform, open-source web server written in Go, with automatic TLS certificate provisioning.

Caddy only supports reverse proxying for HTTP out of the box, but the caddy-l4 plugin allows Caddy to proxy arbitrary streams, which makes it useful for ZNC. When using Caddy in this mode, the web control panel and IRC can be served from a single port.

Build Caddy with the caddy-l4 plugin by following the directions in caddy-l4's README.

caddy-l4 is configured by adding a `layer4` object to the `apps` object of a JSON Caddy configuration, like the one below. Note that the comments must be removed.

{
  "apps": {
    "layer4": {
      "servers": {
        "znc": {
          "listen": [
            ":1337"  // Caddy will listen on this interface
          ],
          "routes": [
            {
              "handle": [
                {
                  // Terminate TLS
                  "handler": "tls",
                  "connection_policies": [
                    {
                      "alpn": [
                        // Caddy always tries to negotiate HTTP/2 by default,
                        // which ZNC's web interface doesn't support, so we need
                        // to override the default protocol list
                        "http/1.1",
                        "http/1.0"
                      ],
                      // Some IRC clients don't support SNI negotiation, so you
                      // need to tell Caddy which certificate to send
                      "default_sni": "your.hostname.com"
                    }
                  ]
                },
                {
                  // Forward cleartext to ZNC
                  "handler": "proxy",
                  "upstreams": [
                    {
                      "dial": [
                        "localhost:2337"  // The address where ZNC is listening
                      ]
                    }
                  ]
                }
              ]
            }
          ]
        }
      }
    }
  }
}

Apache

• You need the proxy_http and rewrite modules to be enabled. On Ubuntu you can do a2enmod proxy_http rewrite and then restart yor Apache instance.

HTTP

As a Subdomain

• The ZNC web control panel can be accessed using (in this case) http://znc.example.com/

<VirtualHost *:80>
	ServerName znc.example.com

	ServerAdmin webmaster@localhost
	DocumentRoot /var/www/html/znc

	ErrorLog ${APACHE_LOG_DIR}/znc-error.log
	CustomLog ${APACHE_LOG_DIR}/znc-access.log combined

	<Location />
		ProxyPass http://localhost:1337/
		ProxyPassReverse http://localhost:1337/
	</Location>
</VirtualHost>

As a Subdirectory

• You must set URIPrefix of the Listener in ZNC to the target location (/znc/ in this example)
• The ZNC web control panel can be accessed using (in this case) http://znc.example.com/znc/

<VirtualHost *:80>
	ServerName znc.example.com

	ServerAdmin webmaster@localhost
	DocumentRoot /var/www/html/znc

	ErrorLog ${APACHE_LOG_DIR}/znc-error.log
	CustomLog ${APACHE_LOG_DIR}/znc-access.log combined

	<Location /znc>
		ProxyPass http://localhost:1337/znc
		ProxyPassReverse http://localhost:1337/znc
	</Location>
</VirtualHost>

HTTPS

As a Subdomain

• The ZNC web control panel can be accessed using (in this case) https://znc.example.com/

<IfModule mod_ssl.c>
<VirtualHost *:443>
	ServerName znc.example.com

	ServerAdmin webmaster@localhost
	DocumentRoot /var/www/html/znc

	ErrorLog ${APACHE_LOG_DIR}/znc-error.log
	CustomLog ${APACHE_LOG_DIR}/znc-access.log combined

	Include /etc/letsencrypt/options-ssl-apache.conf

	<Location />
		ProxyPass http://localhost:4447/
		ProxyPassReverse http://localhost:4447/
	</Location>

	SSLCertificateFile /etc/letsencrypt/live/znc.example.com/fullchain.pem
	SSLCertificateKeyFile /etc/letsencrypt/live/znc.example.com/privkey.pem
</VirtualHost>
</IfModule>

As a Subdirectory

• You must set URIPrefix of the Listener in ZNC to the target location (/znc/ in this example)
• The ZNC web control panel can be accessed using (in this case) https://znc.example.com/znc/

<IfModule mod_ssl.c>
<VirtualHost *:443>
	ServerName znc.example.com

	ServerAdmin webmaster@localhost
	DocumentRoot /var/www/html/znc

	ErrorLog ${APACHE_LOG_DIR}/znc-error.log
	CustomLog ${APACHE_LOG_DIR}/znc-access.log combined

	Include /etc/letsencrypt/options-ssl-apache.conf

	<Location /znc>
		ProxyPass http://localhost:4447/znc
		ProxyPassReverse http://localhost:4447/znc
	</Location>

	SSLCertificateFile /etc/letsencrypt/live/znc.example.com/fullchain.pem
	SSLCertificateKeyFile /etc/letsencrypt/live/znc.example.com/privkey.pem
</VirtualHost>
</IfModule>