coredns/man/coredns-proxyproto.7

.\" Generated by Mmark Markdown Processor - mmark.miek.nl
.TH "COREDNS-PROXYPROTO" 7 "October 2026" "CoreDNS" "CoreDNS Plugins"

.SH "NAME"
.PP
\fIproxyproto\fP \- add PROXY protocol
\[la]https://www.haproxy.org/download/1.8/doc/proxy-protocol.txt\[ra] support.

.SH "DESCRIPTION"
.PP
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.

.SH "SYNTAX"
.PP
.RS

.nf
proxyproto {
    allow <CIDR...>
    default <use|ignore|reject|skip>
    udp\_session\_tracking <duration> [max\_sessions]
    tlv\_metadata
}

.fi
.RE

.PP
If \fB\fCallow\fR is unspecified, PROXY protocol headers are accepted from all IP addresses.
The \fB\fCdefault\fR option controls how connections from sources not listed in \fB\fCallow\fR are handled.
If \fB\fCdefault\fR is unspecified, it defaults to \fB\fCignore\fR.
The possible values are:

.IP \(bu 4
\fB\fCuse\fR: accept and use PROXY protocol headers from these sources
.IP \(bu 4
\fB\fCignore\fR: accept and ignore PROXY protocol headers from other sources
.IP \(bu 4
\fB\fCreject\fR: reject connections with PROXY protocol headers from other sources
.IP \(bu 4
\fB\fCskip\fR: skip PROXY protocol processing for connections from other sources, treating them as normal connections preserving the PROXY protocol headers.


.PP
The \fB\fCudp_session_tracking <duration> [max_sessions]\fR 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 \fB\fCmax_sessions\fR argument caps the number of
concurrent sessions in the LRU cache (default: 10240). This option has no effect for TCP
connections.

.PP
The \fB\fCtlv_metadata\fR option exposes the PROXY Protocol v2 TLV
\[la]https://www.haproxy.org/download/2.3/doc/proxy-protocol.txt\[ra]
(Type\-Length\-Value) vector from the header to downstream plugins via the
\fImetadata\fP
\[la]../metadata/README.md\[ra] plugin. When set, and the \fImetadata\fP plugin is enabled, the
raw TLV vector is published under the label \fB\fCproxyproto/tlv\fR as a hex\-encoded string. Consumers
decode the hex and split it with \fB\fCproxyproto.SplitTLVs\fR from
\fB\fCgithub.com/pires/go-proxyproto\fR to read individual TLVs (e.g. the AWS VPC endpoint ID, SSL
client CN, or vendor\-specific custom TLVs). This option is opt\-in: without it, TLVs are not
captured and no extra per\-connection processing occurs. It applies to all transports: \fB\fCdns://\fR
(UDP and TCP), \fB\fCtls://\fR (DoT), \fB\fChttps://\fR (DoH), \fB\fCgrpc://\fR, \fB\fCquic://\fR (DoQ), and \fB\fChttps3://\fR
(DoH3).

.PP
For the QUIC\-based transports (\fB\fCquic://\fR and \fB\fChttps3://\fR), the PPv2 header arrives as a
standalone first datagram ahead of the QUIC handshake, so TLV capture additionally requires
\fB\fCudp_session_tracking\fR to be enabled; the cached session links the subsequent headerless QUIC
datagrams to the header's source and TLVs.

.SH "METADATA"
.PP
When the \fB\fCtlv_metadata\fR option and the \fImetadata\fP plugin are both enabled, the following metadata
label is made available:

.IP \(bu 4
\fB\fCproxyproto/tlv\fR: the raw PPv2 TLV vector, hex\-encoded. Only set when the request's connection
carried a PPv2 header with at least one TLV.


.SH "EXAMPLES"
.PP
In this configuration, we allow PROXY protocol connections from all IP addresses:

.PP
.RS

.nf
\&. {
    proxyproto
    forward . /etc/resolv.conf
}

.fi
.RE

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

.PP
.RS

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

.fi
.RE

.PP
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:

.PP
.RS

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

.fi
.RE

.PP
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:

.PP
.RS

.nf
\&. {
    proxyproto {
        allow 192.168.1.1/32
        udp\_session\_tracking 28s
    }
    forward . /etc/resolv.conf
}

.fi
.RE

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

.PP
.RS

.nf
\&. {
    proxyproto {
        allow 192.168.1.1/32
        udp\_session\_tracking 28s 20000
    }
    forward . /etc/resolv.conf
}

.fi
.RE

.PP
In this configuration, PPv2 TLVs are exposed to downstream plugins as metadata. The \fImetadata\fP
plugin must also be enabled. Here the \fIlog\fP plugin records the raw TLV vector:

.PP
.RS

.nf
\&. {
    metadata
    proxyproto {
        allow 192.168.1.1/32
        tlv\_metadata
    }
    forward . /etc/resolv.conf
    log . "{remote} {/proxyproto/tlv}"
}

.fi
.RE