Internet Assigned Numbers Authority Hypertext Transfer Protocol (HTTP) Proxy-Status Created 2021-10-22 Last Updated 2024-03-25 Available Formats [IMG] XML [IMG] HTML [IMG] Plain text Registries included below • HTTP Proxy-Status Parameters • HTTP Proxy Error Types HTTP Proxy-Status Parameters Registration Procedure(s) Expert Review Expert(s) Mark Nottingham Reference [RFC9209] Note New Proxy-Status parameters and proxy error types, along with changes to existing ones, can be requested using the [registry interface] or the ietf-http-wg@w3.org mailing list. Available Formats [IMG] CSV Name Description Reference error The error parameter's value is a Token that is a proxy error type. When present, it indicates that the intermediary [RFC9209] encountered an issue when obtaining this response. next-hop The next-hop parameter's value is a String or Token that identifies the intermediary or origin server selected (and [RFC9209] used, if contacted) to obtain this response. It might be a hostname, IP address, or alias. next-protocol The next-protocol parameter's value indicates the Application-Layer Protocol Negotiation (ALPN) protocol identifier [RFC9209] [RFC7301] of the protocol used by the intermediary to connect to the next hop when obtaining this response. received-status The received-status parameter's value indicates the HTTP status code that the intermediary received from the next-hop [RFC9209] server when obtaining this response. details The details parameter's value is a String containing additional information not captured anywhere else. This can [RFC9209] include implementation-specific or deployment-specific information. next-hop-aliases A string containing one or more DNS aliases or canonical names used to establish a proxied connection to the next [RFC9532] hop. HTTP Proxy Error Types Registration Procedure(s) Expert Review Expert(s) Mark Nottingham Reference [RFC9209] Note New Proxy-Status parameters and proxy error types, along with changes to existing ones, can be requested using the [registry interface] or the ietf-http-wg@w3.org mailing list. Available Formats [IMG] CSV Recommended Response Only Name Description Extra Parameters HTTP Status Generated by Reference Notes Code Intermediaries The intermediary encountered a timeout dns_timeout when trying to find an IP None 504 true [RFC9209] address for the next-hop hostname. - rcode: A String conveying the DNS RCODE The intermediary that indicates the error encountered a DNS error type. See [RFC9499], dns_error when trying to find an IP Section 3. 502 true [RFC9209] address for the next-hop hostname. - info-code: An Integer conveying the Extended DNS Error Code INFO-CODE. See [RFC8914]. The intermediary cannot determine the appropriate next hop to use for this request; for example, it may not be configured. Note that this error is destination_not_found specific to gateways, None 500 true [RFC9209] which typically require specific configuration to identify the "backend" server; forward proxies use in-band information to identify the origin server. The intermediary considers the next hop to be unavailable; e.g., destination_unavailable recent attempts to None 503 true [RFC9209] communicate with it may have failed, or a health check may indicate that it is down. The intermediary is destination_ip_prohibited configured to prohibit None 502 true [RFC9209] connections to the next-hop IP address. The intermediary cannot destination_ip_unroutable find a route to the None 502 true [RFC9209] next-hop IP address. The intermediary's connection_refused connection to the next None 502 true [RFC9209] hop was refused. The intermediary's connection to the next connection_terminated hop was closed before a None 502 false [RFC9209] complete response was received. The intermediary's connection_timeout attempt to open a None 504 true [RFC9209] connection to the next hop timed out. The intermediary was expecting data on a connection_read_timeout connection (e.g., part of None 504 false [RFC9209] a response) but did not receive any new data in a configured time limit. The intermediary was attempting to write data connection_write_timeout to a connection but was None 504 false [RFC9209] not able to (e.g., because its buffers were full). The intermediary is configured to limit the connection_limit_reached number of connections it None 503 true [RFC9209] has to the next hop, and that limit has been exceeded. The intermediary encountered a TLS error Not appropriate when tls_protocol_error when communicating with None 502 false [RFC9209] a TLS alert is the next hop, either received; see during the handshake or tls_alert_received. afterwards. The intermediary encountered an error when tls_certificate_error verifying the certificate None 502 true [RFC9209] presented by the next hop. - alert-id: An Integer containing the applicable value from the [TLS Alerts registry]. See The intermediary received [RFC8446]. tls_alert_received a TLS alert from the next 502 false [RFC9209] hop. - alert-message: A Token or String containing the applicable description string from the [TLS Alerts registry]. See [RFC8446]. The intermediary is generating a client (4xx) - status-code: An Integer This type helps response on the origin's containing the generated The distinguish between behalf. Applicable status status code. applicable responses generated http_request_error codes include (but are 4xx status true [RFC9209] by intermediaries not limited to) 400, 403, - status-phrase: A String code from those generated 405, 406, 408, 411, 413, containing the generated by the origin. 414, 415, 416, 417, and status phrase. 429. The intermediary rejected the HTTP request based on http_request_denied its configuration and/or None 403 true [RFC9209] policy settings. The request wasn't forwarded to the next hop. The intermediary received http_response_incomplete an incomplete response to None 502 false [RFC9209] the request from the next hop. - header-section-size: An Integer indicating how The intermediary received large the received a response to the request headers were. Note that http_response_header_section_size whose header section was they might not be 502 false [RFC9209] considered too large. complete; i.e., the intermediary may have discarded or refused additional data. - header-name: A String indicating the name of The intermediary received the header field that a response to the request triggered the error. http_response_header_size containing an individual 502 false [RFC9209] header field line that - header-size: An Integer was considered too large. indicating the size of the header field that triggered the error. - body-size: An Integer indicating how large the The intermediary received received body was. Note http_response_body_size a response to the request that it may not have been 502 false [RFC9209] whose body was considered complete; i.e., the too large. intermediary may have discarded or refused additional data. - trailer-section-size: An Integer indicating how The intermediary received large the received a response to the request trailers were. Note that http_response_trailer_section_size whose trailer section was they might not be 502 false [RFC9209] considered too large. complete; i.e., the intermediary may have discarded or refused additional data. - trailer-name: A String indicating the name of The intermediary received the trailer field that a response to the request triggered the error. http_response_trailer_size containing an individual 502 false [RFC9209] trailer field line that - trailer-size: An was considered too large. Integer indicating the size of the trailer field that triggered the error. - coding: A Token The intermediary containing the specific http_response_transfer_coding encountered an error coding (from the [HTTP 502 false [RFC9209] decoding the transfer Transfer Coding coding of the response. Registry]) that caused the error. The intermediary - coding: A Token encountered an error containing the specific http_response_content_coding decoding the content coding (from the [HTTP 502 false [RFC9209] coding of the response. Content Coding Registry]) that caused the error. The intermediary reached http_response_timeout a configured time limit None 504 false [RFC9209] waiting for the complete response. The process of negotiating an upgrade of http_upgrade_failed the HTTP version between None 502 true [RFC9209] the intermediary and the next hop failed. The intermediary encountered an HTTP protocol error when http_protocol_error communicating with the None 502 false [RFC9209] next hop. This error should only be used when a more specific one is not defined. The intermediary The most generated the response appropriate proxy_internal_response itself without attempting None status code true [RFC9209] to connect to the next for the hop. response The intermediary proxy_internal_error encountered an internal None 500 true [RFC9209] error unrelated to the origin. The intermediary proxy_configuration_error encountered an error None 500 true [RFC9209] regarding its configuration. The intermediary tried to forward the request to proxy_loop_detected itself, or a loop has None 502 true [RFC9209] been detected using different means (e.g., [RFC8586]). Licensing Terms