TheViarequest andresponse header is added byproxies, both forward and reverse.It is used for tracking message forwards, avoiding request loops, and identifying the protocol capabilities of senders along the request/response chain.

Syntax

Via: [<protocol-name>/]<protocol-version> <host>[:<port>]Via: [<protocol-name>/]<protocol-version> <pseudonym>

Directives

<protocol-name>Optional

The name of the protocol used, such as "HTTP".

<protocol-version>

The version of the protocol used, such as "1.1".

<host>

Public proxy URL and optional<port>.If a host is not provided, then a<pseudonym> must be used.

<pseudonym>

Name/alias of an internal proxy.If a pseudonym is not provided, then a<host> must be used.

Examples

Via: 1.1 vegurVia: HTTP/1.1 GWAVia: 1.0 fred, 1.1 p.example.net

Specifications

Browser compatibility

See also

• X-Forwarded-For
• Heroku's proxy library Vegur