blog: how to enable ipv6 in applications

content/u/blog/how-to-enable-ipv6-in-applications/contents.lr

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+title: How to enable IPv6 in applications
+---
+pub_date: 2019-09-26
+---
+author: Team ungleich
+---
+twitter_handle: ungleich
+---
+abstract:
+New to IPv6? Wondering how to enable IPv6 in your favorite
+application? Then this blog entry is for you.
+---
+body:
+
+In this blog article you'll find some hints on how to enable IPv6 for
+various applications.
+
+## nginx
+
+The web server nginx by default only listens to IPv4 if you use
+the standard `listen *:80;` directive. To enable IPv6, use
+`listen [::]:80;`. So for a dual stack server, your configuration
+could look as follows:
+
+
+```
+server {
+    listen *:80;
+    listen [::]:80;
+
+    ...
+
+}
+
+```
+
+## haproxy
+
+There are various interesting configuration options in HAProxy related
+to IPv6. Let's have a look at each of them!
+
+To enable IPv6 transport for the local logging, use `log [::1]` in the
+global section:
+
+```
+global
+    log      [::1] local2
+    ...
+
+```
+
+If you want a frontend to listen to either IPv6 or IPv4 only, you can
+use the `ipv6@` prefix as follows:
+
+```
+# IPv6 http frontend
+frontend httpipv6
+    bind ipv6@:80
+    mode http
+
+
+# IPv4 http frontend
+frontend httpipv4
+    bind ipv4@:80
+    mode http
+    ...
+
+```
+
+If you want to connect to the backends only via a specific protocol,
+we can use the prefix syntax there as well:
+
+```
+backend httpipv4
+    mode http
+    use-server ungleich.ch if { hdr(host) -i ungleich.ch }
+    server ungleich.ch ipv6@ungleich.ch
+    ...
+```
+
+To proxy IPv6 requests to IPv4 only [twitter](https://twitter.com), you could
+use the following configuration:
+
+```
+# ipv6 https
+frontend httpsipv6
+    bind ipv6@:443
+    mode tcp
+    option tcplog
+    tcp-request inspect-delay 5s
+    tcp-request content accept if { req_ssl_hello_type 1 }
+    default_backend httpsipv6
+
+backend httpsipv6
+    mode tcp
+    use-server twitter.com if { req_ssl_sni -i twitter.com }
+    server twitter.com ipv4@twitter.com
+```
+
+
+## Other applications
+
+If you know about other applications or want to enhance one of our
+configuration, we invite you to join the [IPv6
+chat](https://IPv6.chat) or [write to us on
+Twitter](https://twitter.com/ungleich).