coredns/man/coredns-https3.7

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.TH "COREDNS-HTTPS3" 7 "October 2026" "CoreDNS" "CoreDNS Plugins"

.SH "NAME"
.PP
\fIhttps3\fP - configures DNS-over-HTTPS/3 (DoH3) server options.

.SH "DESCRIPTION"
.PP
The \fIhttps3\fP plugin allows you to configure parameters for the DNS-over-HTTPS/3 (DoH3) server to fine-tune the security posture and performance of the server. HTTPS/3 uses QUIC as the underlying transport.

.PP
This plugin can only be used once per HTTPS3 listener block.

.SH "SYNTAX"
.PP
.RS

.nf
https3 {
    max\_streams POSITIVE\_INTEGER
    max\_connections POSITIVE\_INTEGER
}

.fi
.RE

.IP \(bu 4
\fB\fCmax_streams\fR limits the number of concurrent QUIC streams per connection. This helps prevent unbounded streams on a single connection, exhausting server resources. The default value is 256 if not specified. Set to 0 to use underlying QUIC transport default.
.IP \(bu 4
\fB\fCmax_connections\fR limits the number of concurrent HTTPS/3 connections accepted by the server. The default value is 200 if not specified. Connections above the configured limit are rejected. Set to 0 to disable the CoreDNS connection limit.


.SH "EXAMPLES"
.PP
Set custom limits for maximum streams:

.PP
.RS

.nf
https3://.:443 {
    tls cert.pem key.pem
    https3 {
        max\_streams 50
    }
    whoami
}

.fi
.RE

.PP
Set values to 0 for QUIC transport default, matching CoreDNS behaviour before v1.14.0:

.PP
.RS

.nf
https3://.:443 {
    tls cert.pem key.pem
    https3 {
        max\_streams 0
    }
    whoami
}

.fi
.RE