Internet Assigned Numbers Authority Hypertext Transfer Protocol (HTTP) Proxy-Status Created 2021-10-22 Last Updated 2023-09-26 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. 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 dns_timeout timeout when None 504 true [RFC9209] trying to find an IP address for the next-hop hostname. - rcode: A String conveying the The intermediary DNS RCODE that indicates the encountered a DNS error type. See error when trying [RFC-ietf-dnsop-rfc8499bis-10], dns_error 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 specific to destination_not_found gateways, which None 500 true [RFC9209] 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., recent attempts to destination_unavailable communicate with None 503 true [RFC9209] it may have failed, or a health check may indicate that it is down. The intermediary is configured to destination_ip_prohibited prohibit None 502 true [RFC9209] connections to the next-hop IP address. The intermediary cannot find a destination_ip_unroutable route to the None 502 true [RFC9209] next-hop IP address. The intermediary's connection_refused connection to the None 502 true [RFC9209] next hop was refused. The intermediary's connection to the connection_terminated next hop was None 502 false [RFC9209] closed before a complete response was received. The intermediary's attempt to open a connection_timeout connection to the None 504 true [RFC9209] next hop timed out. The intermediary was expecting data on a connection (e.g., part of a connection_read_timeout response) but did None 504 false [RFC9209] not receive any new data in a configured time limit. The intermediary was attempting to write data to a connection_write_timeout connection but was None 504 false [RFC9209] not able to (e.g., because its buffers were full). The intermediary is configured to limit the number connection_limit_reached of connections it None 503 true [RFC9209] has to the next hop, and that limit has been exceeded. The intermediary encountered a TLS error when Not appropriate when tls_protocol_error communicating with None 502 false [RFC9209] a TLS alert is the next hop, received; see either during the tls_alert_received. handshake or afterwards. The intermediary encountered an error when tls_certificate_error verifying the None 502 true [RFC9209] certificate presented by the next hop. - alert-id: An Integer containing the applicable value The intermediary from the [TLS Alerts registry]. received a TLS See [RFC8446]. tls_alert_received alert from the 502 false [RFC9209] next 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 response on the containing the generated status This type helps origin's behalf. code. The distinguish between http_request_error Applicable status applicable true [RFC9209] responses generated codes include (but - status-phrase: A String 4xx status by intermediaries are not limited containing the generated status code from those generated to) 400, 403, 405, phrase. by the origin. 406, 408, 411, 413, 414, 415, 416, 417, and 429. The intermediary rejected the HTTP request based on its configuration http_request_denied and/or policy None 403 true [RFC9209] settings. The request wasn't forwarded to the next hop. The intermediary received an http_response_incomplete incomplete None 502 false [RFC9209] response to the request from the next hop. The intermediary - header-section-size: An received a Integer indicating how large the response to the received headers were. Note that http_response_header_section_size request whose they might not be complete; 502 false [RFC9209] header section was i.e., the intermediary may have considered too discarded or refused additional large. data. The intermediary - header-name: A String received a indicating the name of the response to the header field that triggered the request containing error. http_response_header_size an individual 502 false [RFC9209] header field line - header-size: An Integer that was indicating the size of the considered too header field that triggered the large. error. The intermediary - body-size: An Integer received a indicating how large the response to the received body was. Note that it http_response_body_size request whose body may not have been complete; 502 false [RFC9209] was considered too i.e., the intermediary may have large. discarded or refused additional data. The intermediary - trailer-section-size: An received a Integer indicating how large the response to the received trailers were. Note http_response_trailer_section_size request whose that they might not be complete; 502 false [RFC9209] trailer section i.e., the intermediary may have was considered too discarded or refused additional large. data. The intermediary - trailer-name: A String received a indicating the name of the response to the trailer field that triggered the request containing error. http_response_trailer_size an individual 502 false [RFC9209] trailer field line - trailer-size: An Integer that was indicating the size of the considered too trailer field that triggered the large. error. The intermediary - coding: A Token containing the encountered an specific coding (from the [HTTP http_response_transfer_coding error decoding the Transfer Coding Registry]) that 502 false [RFC9209] transfer coding of caused the error. the response. The intermediary - coding: A Token containing the encountered an specific coding (from the [HTTP http_response_content_coding error decoding the Content Coding Registry]) that 502 false [RFC9209] content coding of caused the error. the response. The intermediary reached a http_response_timeout configured time None 504 false [RFC9209] limit waiting for the complete response. The process of negotiating an upgrade of the http_upgrade_failed HTTP version None 502 true [RFC9209] between the intermediary and the next hop failed. The intermediary encountered an HTTP protocol error when http_protocol_error communicating with None 502 false [RFC9209] the next hop. This error should only be used when a more specific one is not defined. The intermediary The most generated the appropriate proxy_internal_response response itself None status code true [RFC9209] without attempting for the to connect to the response next hop. The intermediary encountered an proxy_internal_error internal error None 500 true [RFC9209] unrelated to the origin. The intermediary proxy_configuration_error encountered an None 500 true [RFC9209] error regarding its configuration. The intermediary tried to forward the request to proxy_loop_detected itself, or a loop None 502 true [RFC9209] has been detected using different means (e.g., [RFC8586]). Licensing Terms