This plugin adds support for the PROXY protocol version 1 and 2. It allows CoreDNS to receive connections from a load balancer or proxy that uses the PROXY protocol to forward the original client's IP address and port information.

Syntax

proxyproto {
    allow <CIDR...>
    default <use|ignore|reject|skip>
    udp_session_tracking <duration> [max_sessions]
}

If allow is unspecified, PROXY protocol headers are accepted from all IP addresses. The default option controls how connections from sources not listed in allow are handled. If default is unspecified, it defaults to ignore. The possible values are:

use: accept and use PROXY protocol headers from these sources
ignore: accept and ignore PROXY protocol headers from other sources
reject: reject connections with PROXY protocol headers from other sources
skip: skip PROXY protocol processing for connections from other sources, treating them as normal connections preserving the PROXY protocol headers.

The udp_session_tracking <duration> [max_sessions] option enables UDP session state tracking for Cloudflare Spectrum's PROXY Protocol v2 over UDP. Spectrum sends the PPv2 header as a standalone first datagram (with no DNS payload). Subsequent datagrams from the same client arrive without any header. When this option is set to a positive duration, the real client address from the header-only datagram is cached (keyed by the Spectrum-side remote address) for that duration and automatically applied to all subsequent headerless datagrams within that window. The TTL is refreshed on each matching packet. The optional max_sessions argument caps the number of concurrent sessions in the LRU cache (default: 10240). This option has no effect for TCP connections.

Examples

In this configuration, we allow PROXY protocol connections from all IP addresses:

. {
    proxyproto
    forward . /etc/resolv.conf
}

In this configuration, we only allow PROXY protocol connections from the specified CIDR ranges and ignore proxy protocol headers from other sources:

. {
    proxyproto {
        allow 192.168.1.1/32 192.168.0.1/32
    }
    forward . /etc/resolv.conf
}

In this configuration, we only allow PROXY protocol headers from the specified CIDR ranges and reject connections without valid PROXY protocol headers from those sources:

. {
    proxyproto {
        allow 192.168.1.1/32
        default reject
    }
    forward . /etc/resolv.conf
}

In this configuration, we enable UDP session tracking for Cloudflare Spectrum's PPv2-over-UDP with a 28-second TTL (slightly shorter than Spectrum's 30-second UDP idle timeout) and the default session cap of 10240:

. {
    proxyproto {
        allow 192.168.1.1/32
        udp_session_tracking 28s
    }
    forward . /etc/resolv.conf
}

In this configuration, the session cap is raised to 20480:

. {
    proxyproto {
        allow 192.168.1.1/32
        udp_session_tracking 28s 20000
    }
    forward . /etc/resolv.conf
}