Difference between revisions of "Tech pages/XEP-0368"

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Tech pages/XEP-0368 (view source)

Revision as of 18:47, 19 June 2020

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Add transparent proxying nginx -> ejabberd
(Add transparent proxying nginx -> ejabberd)
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[https://xmpp.org/extensions/xep-0368.html XEP-0368] can be used to provide encrypted XMPP service as well as HTTPS on the same port by utilizing [https://en.wikipedia.org/wiki/Application-Layer_Protocol_Negotiation ALPN TLS extension].
Port 443 is commonly allowed by firewalls. To run multiple services on one port a proxy is needed to split the traffic between HTTP server and the XMPP server.
Note that this will not hide XMPP traffic from sufficiently intelligent firewalls as ALPN value is still sent unencrypted.
This page presents configuration hints for several popular proxies.
__TOC__
== nginx ==
Nginx since version 1.13.10 has additional variable (<code>$ssl_preread_alpn_protocols</code>) available when using [https://nginx.org/en/docs/stream/ngx_stream_ssl_preread_module.html ngx_stream_ssl_preread] module (this module must be included when compiling nginx).
The configuration below routes traffic with ALPN xmpp-client to server xmppserver and the rest (including HTTPS) to httpserver.
<nowiki>
stream {
    upstream httpserver {
        server httpserver:8181;
    }
    upstream xmppserver {
        server xmppserver:5223;
    }
    upstream turnserver {
        server turnserver:3477;
    }
    map $ssl_preread_alpn_protocols $upstream {
        default httpserver;
        "xmpp-client" xmppserver;
        "stun.turn" turnserver;
        "stun.nat-discovery" turnserver;
    }
    server {
        listen 443;
        ssl_preread on;
        proxy_pass $upstream;
    }
}
</nowiki>
Nginx will route only TLS traffic in this configuration so this configuration will work only with direct TLS (<code>_xmpps-client</code> SRV record). Connections that start unencrypted and then request encryption (STARTTLS, <code>_xmpp-client</code> record) will not work.
== sslh ==
Here is a sample sslh.conf (Using at least [http://www.rutschle.net/tech/sslh/README.html sslh] 1.18) to support [https://xmpp.org/extensions/xep-0368.html XEP-0368] among other things:
Here is a sample sslh.conf (Using at least [http://www.rutschle.net/tech/sslh/README.html sslh] 1.18) to support [https://xmpp.org/extensions/xep-0368.html XEP-0368] among other things:


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# 5222 is a regular/plain/starttls xmpp port (prosody c2s_ports, ejabberd listen with starttls: true)
# 5222 is a regular/plain/starttls xmpp port (prosody c2s_ports, ejabberd listen with starttls: true)
# 994 is "direct-tls" imap port, imaps (dovecot etc)
# 994 is "direct-tls" imap port, imaps (dovecot etc)
# 3477 is TURNS (TURN-over-TLS) port (coturn etc) NOTE: coturn by default (newer versions) rejects connections from localhost, you'd either need transparent mode, or to turn this off and open up all the risks it entails, for it to accept connections from sslh
   
   
protocols:
protocols:
(
(
     { name: "tls";    host: "127.0.0.1"; port: "442";  alpn_protocols: [ "h2", "http/1.1" ]; },                 # https most common case
     { name: "tls";    host: "127.0.0.1"; port: "442";  alpn_protocols: [ "h2", "http/1.1" ]; },                 # https most common case
     { name: "tls";    host: "127.0.0.1"; port: "5223"; alpn_protocols: [ "xmpp-client" ]; },                   # check for XEP-0368 xmpp tls (this needs to be above SNI check below because XEP-0368 would send example.org in SNI)
     { name: "tls";    host: "127.0.0.1"; port: "5223"; alpn_protocols: [ "xmpp-client" ]; },                     # check for XEP-0368 xmpp tls (this needs to be above SNI check below because XEP-0368 would send example.org in SNI)
     { name: "tls";    host: "127.0.0.1"; port: "442";  sni_hostnames:  [ "www.example.org", "example.org" ]; }, # specific hostnames go to https
     { name: "tls";    host: "127.0.0.1"; port: "442";  sni_hostnames:  [ "www.example.org", "example.org" ]; }, # specific hostnames go to https
     { name: "tls";    host: "127.0.0.1"; port: "994";  sni_hostnames:  [ "imap.example.org" ]; },               # other hostnames go to imaps
    { name: "tls";    host: "127.0.0.1"; port: "3477"; alpn_protocols: [ "stun.turn", "stun.nat-discovery" ]; }, # turn should send ALPN, but if it doesn't...
     { name: "tls";    host: "127.0.0.1"; port: "442"; },                                                       # anything else TLS assume for https
    { name: "tls";    host: "127.0.0.1"; port: "3477"; sni_hostnames:  [ "turn.example.org" ]; },                # we can also match turn on SNI
     { name: "ssh";    host: "127.0.0.1"; port: "22"; },                                                         # ssh goes to ssh
     { name: "tls";    host: "127.0.0.1"; port: "994";  sni_hostnames:  [ "imap.example.org" ]; },               # other hostnames go to imaps
     { name: "xmpp";    host: "127.0.0.1"; port: "5222"; },                                                       # xmpp goes to regular xmpp port
     { name: "tls";    host: "127.0.0.1"; port: "442"; },                                                         # anything else TLS assume for https
     { name: "timeout"; host: "127.0.0.1"; port: "442"; }                                                         # send everything unknown to https
     { name: "ssh";    host: "127.0.0.1"; port: "22"; },                                                         # ssh goes to ssh
     { name: "xmpp";    host: "127.0.0.1"; port: "5222"; },                                                       # xmpp goes to regular xmpp port
     { name: "timeout"; host: "127.0.0.1"; port: "442"; }                                                         # send everything unknown to https
);
);


on-timeout: "timeout"; # if timeout elapses (2 seconds here) go to https
on-timeout: "timeout"; # if timeout elapses (2 seconds here) go to https
</nowiki>
</nowiki>
 
Another (incorrectly named) example can be found at the [https://wiki.debian.org/InstallingProsody#XMPP_over_HTTPS Debian Wiki]
 
== Transparent Proxying ==
 
If your XMPP server and protocol multiplexer are supporting the proxy protocol, you should consider enabling it.
That way your XMPP server will see the real IPs of clients that connect to it.
 
=== Nginx ===
To enable the proxy protocol in nginx, modify your configuration as follows:
 
<nowiki>
stream {
    ...
 
    server {
        listen 443;
 
        ssl_preread on;
        proxy_pass $upstream;
        proxy_protocol: on; <-- add this line
    }
}
</nowiki>
 
=== ejabberd ===
In case of ejabberd, you want to add an additional handler that accepts the proxy protocol:
 
<nowiki>
listen:
  ...
  -
    port: 5225
    use_proxy_protocol: true <-- Important!
    ip: "::"
    module: ejabberd_c2s
    max_stanza_size: 262144
    shaper: c2s_shaper
    access: c2s
    tls: true
    protocol_options: 'TLS_OPTIONS'
  ...
</nowiki>
 
Note that you should only connect to this handler via the proxy protocol, as other connections will be refused.


This should now be possible with nginx following something like this:
Now ejabberd will display the real IPs of users that connect to your server via multiplexing over port 443.
http://mailman.nginx.org/pipermail/nginx/2018-March/055798.html
https://nginx.org/en/docs/stream/ngx_stream_ssl_preread_module.html
Remove this blurb when actual example documentation is added.


Another (incorrectly named) example can be found at the [https://wiki.debian.org/InstallingProsody#XMPP_over_HTTPS Debian Wiki]
== DNS setup ==


You then need to setup your [https://wiki.xmpp.org/web/SRV_Records SRV Records] so clients can find it, personally I have mine set up like so (for a JID like me@example.org):
You then need to setup your [https://wiki.xmpp.org/web/SRV_Records SRV Records] so clients can find it, personally I have mine set up like so (for a JID like me@example.org):
Vanitasvitae
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