Proxy Protocol

The PROXY protocol provides a means of passing connection information between layers of the proxy infrastructure. Without the PROXY protocol, Traffic Server would only have connection information from the previous hop connecting to Traffic Server and not the actual originating client connection information. This can be done over either HTTP or TLS connections.


The current implementation doesn’t support TLV fields of Version 2.

The Proxy Protocol must be enabled on each port. See proxy.config.http.server_ports for information on how to enable the Proxy Protocol on a port. Once enabled, all incoming requests must be prefaced with the PROXY v1/v2 header. Any request not preface by this header will be dropped.

As a security measure, an optional list of trusted IP addresses may be configured with proxy.config.http.proxy_protocol_allowlist.


If the allowlist is configured, requests will only be accepted from these IP addresses and must be prefaced with the PROXY v1/v2 header.

  1. HTTP Forwarded Header

The client IP address in the PROXY protocol header is passed to the origin server via an HTTP Forwarded: header. See proxy.config.http.insert_forwarded for configuration information. Detection of the PROXY protocol header is automatic. If the PROXY header precludes the request, it will automatically be parse and made available to the Forwarded: request header sent to the origin server.

  1. Outbound PROXY protocol

See proxy.config.http.proxy_protocol_out for configuration information.


As an example, consider the following topology:

PROXY protocol transformed into a Forwarded: header

PROXY protocol header flow

Without the PROXY protocol header, the client IP would only be reported accurately to the Load Balancer. Traffic Server would only see the connection from the Load Balancer. Similarly, the Web Server would only see the connection from Traffic Server. In the example above, if the client initiated a TLS connection, the Web Server would see the connection originating from Traffic Server at

Forwarded: for=;by=;proto=https;

If the Load Balancer has the Proxy Protocol enabled, requests sent through the Load Balancer will be preceded with the PROXY header. Traffic Server will detect the PROXY header and transform that into the Forwarded: HTTP header if configured to insert the Forwarded: header with the for parameter. In the example above, if the client initiated a TLS connection, the Web Server can use the Forwarded: header to determine the TLS connection originated from the client at

Forwarded: for=;by=;proto=https;