Proxy Protocol support

• 1: The working mechanism behind the Proxy Protocol
• 2: Proxy Protocol: configuration and output examples

1 - The working mechanism behind the Proxy Protocol

This section describes how AxoSyslog supports the Proxy Protocol.

The working mechanism behind the Proxy Protocol

When using the Proxy Protocol during load balancing, AxoSyslog detects the information behind connections connected to the load balancer, then parses the injected information into the following macros:

2 - Proxy Protocol: configuration and output examples

This section provides information about enabling Proxy Protocol support in your network() source options, and an example configuration and output to illustrate how the Proxy Protocol method works in AxoSyslog.

For more information about the working mechanism of the Proxy Protocol, see The working mechanism behind the Proxy Protocol.

Enabling Proxy Protocol support for your network() source options

Unless you enable Proxy Protocol support for your network() source, AxoSyslog identifies every connection that is connected to the load balancers identically by default, regardless of the source IP or the source protocol.

To enable Proxy Protocol for your network() source, set the transport() parameter of your network() source to proxied-tcp, proxied-tls-passthrough, or proxied-udp, depending on your preference and configuration.

proxied-tls can be used in complex MITM (man in the middle) configurations, where the proxy header is sent encrypted within the same TLS session as the proxied messages.

When you enable Proxy Protocol support for your network() source, you can use the following configuration example with your AxoSyslog application.

Configuration

The following code sample illustrates how you can use the Proxy Protocol in your AxoSyslog configuration (using the transport() parameter set to proxied-tls-passthrough).

   @version: 3.35
    
    source s_tcp_pp {
      network (
        port(6666)
        transport("proxied-tls-passthrough")
        tls(
            key-file("/certs/certs/server/server.rsa")
            cert-file("/certs/certs/server/server.crt")
            ca-dir("/certs/certs/CA")
            peer-verify("required-trusted")
        )
      );
    };
    
    destination d_file {
      file("/var/log/proxy-proto.log" template("$(format-json --scope nv-pairs)\n"));
    };
    
    log {
      source(s_tcp_pp);
      destination(d_file);
    };

With this configuration, the Proxy Protocol method will perform injecting the information of the original connection into the forwarded TCP session, based on the working mechanism described in The working mechanism behind the Proxy Protocol.

The following example illustrates how the parsed macros will appear in the output.

Example: Output for the PROXY TCP4 192.168.1.1 10.10.0.1 1111 2222 input header

With the PROXY TCP4 192.168.1.1 10.10.0.1 1111 2222 input header, the output looks like this:

   {"SOURCE":"s_tcp_pp","PROXIED_SRCPORT":"1111","PROXIED_SRCIP":"192.168.1.1","PROXIED_IP_VERSION":"4","PROXIED_DSTPORT":"2222","PROXIED_DSTIP":"10.10.0.1","PROGRAM":"TestMsg","MESSAGE":"","LEGACY_MSGHDR":"TestMsg","HOST_FROM":"localhost","HOST":"localhost"}

Note that the macros that AxoSyslog adds to the message appear in the output.

Enabling Proxy Protocol v2 support over UDP

Available in AxoSyslog version 4.25 and later.

To receive UDP syslog messages from a load balancer that injects HAProxy Proxy Protocol v2 headers, set transport("proxied-udp") on your network() or syslog() source.

Using the network() driver (BSD syslog/RFC3164 format):

source s_udp_pp {
    network(
        ip("0.0.0.0")
        port(514)
        transport("proxied-udp")
    );
};

Using the syslog() driver (IETF syslog/RFC5424 format):

source s_syslog_udp_pp {
    syslog(
        ip("0.0.0.0")
        port(514)
        transport("proxied-udp")
    );
};

After parsing, the original client address and port are available as ${SOURCEIP}, ${SOURCEPORT}, ${DESTIP}, and ${DESTPORT} macros, the same as for TCP-based proxied transports.