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