Squid_ The Definitive Guide - Duane Wessels [122]
10.4.3
403
Forbidden
10.4.4
404
Not Found
10.4.5
405
Method Not Allowed
10.4.6
406
Not Acceptable
10.4.7
407
Proxy Authentication Required
10.4.8
408
Request Timeout
10.4.9
409
Conflict
10.4.10
410
Gone
10.4.11
411
Length Required
10.4.12
412
Precondition Failed
10.4.13
413
Request Entity Too Large
10.4.14
414
Request-URI Too Long
10.4.15
415
Unsupported Media Type
10.4.16
416
Requested Range Not Satisfiable
10.4.17
417
Expectation Failed
10.4.18
5xx
Server Error
10.5
500
Internal Server Error
10.5.1
501
Not Implemented
10.5.2
502
Bad Gateway
10.5.3
503
Service Unavailable
10.5.4
504
Gateway Timeout
10.5.5
505
HTTP Version Not Supported
10.5.6
6xx
Proxy Error
N/A
600
Unparseable Response Headers (Squid-specific)
N/A
You'll see status code 0 in the access.log if Squid doesn't receive any response from the origin server. You'll see status code 600 if Squid received a response but couldn't find any HTTP headers. In a small fraction of cases, certain origin servers send only the response body and omit any headers.
access.log Peering Codes
The following codes may appear in the ninth field of the access.log. Refer to Section 10.10 for a description of how Squid selects the next-hop for cache misses.
NONE
This indicates that Squid didn't communicate with any other servers (neighbors, origin) for this request. You'll see it in association with various types of cache hits, denied requests, cache manager requests, errors, and all ICP queries.
DIRECT
Squid forwarded the request directly to the origin server. The second half of the field shows the origin server's IP address, or hostname if you've disabled log_ip_on_direct.
SIBLING_HIT
Squid sent the request to this sibling cache after the sibling returned an ICP or HTCP hit.
PARENT_HIT
Squid sent the request to this parent cache after the parent returned an ICP or HTCP hit.
DEFAULT_PARENT
Squid selected this parent because it was marked as default on the cache_peer line in squid.conf.
FIRST_UP_PARENT
Squid forwarded the request to this parent because it is the first parent in the list known to be alive.
FIRST_PARENT_MISS
Squid forwarded the request to the parent cache that was first to respond with an ICP/HTCP miss message. In other words, for this particular ICP/HTCP query, at this particular time, the selected parent had the best round-trip time. Note that measured RTTs may be artificially adjusted by the weight option to the cache_peer directive.
CLOSEST_PARENT_MISS
Squid selected this parent because it reports the lowest RTT to the origin server. This occurs only if both caches have netdb enabled (see Section 10.5), and the origin server (or other servers on its subnet) returns ICMP pings.
CLOSEST_PARENT
This is similar to CLOSEST_PARENT_MISS, except that the RTT measurements don't come from the ICP/HTCP reply messages. Instead, they come from older measurements saved by Squid, such as the netdb exchange feature.
CLOSEST_DIRECT
Squid forwarded the request to the origin server based on netdb measurements. This happens if any of these conditions occur:
The RTT between Squid and the origin server is less than the configured minimum_direct_rtt value.
The measured number of router hops between Squid and the origin server is less than the configured minimum_direct_hops value.
The RTT values returned in ICP/HTCP replies indicate that Squid is closer to the origin server than any of its neighbors.
ROUNDROBIN_PARENT
Squid forwarded the request to this parent because the round-robin option was set, and it had the lowest usage counter.
CD_PARENT_HIT
Squid forwarded the request to this parent based on the Cache Digest algorithm (see Section 10.7).
CD_SIBLING_HIT
Squid forwarded the request to this sibling based on the Cache Digest algorithm.
CARP
Squid selected this parent based on the Cache Array Routing Protocol algorithm (see Section 10.9).
ANY_PARENT
Squid selected this parent as a last