Ubuntu Manpage: fetch-crl - retrieve certificate revocation lists

NAME

       fetch-crl - retrieve certificate revocation lists

SYNOPSIS

       fetch-crl   [-c config]   [-v[v..]]    [-q]   [-h]   [--inet6glue]  [-l infopath]  [-o outputpath]
       [-s statepath]    [-a agingtolerance]    [-T httptimeout]     [-r randomwait]     [-p parallelism]
       [--formats openssl|pem|der|nss] ..  [--define key=value] ..  [--cfgdir dirname]

DESCRIPTION

The fetch-crl utility will retrieve certificate revocation lists (CRLs) for a set of
installed trust anchors, based on crl_url files or IGTF-style info files. It will install
these for use with OpenSSL, NSS or third-party tools.

It works based on a list of trust anchors, for each of which one or more CRLs should be
installed in a CRL store. And for each of these CRLs, one or more URLs can be specified
from which the specific CRL can be retrieved. There are several supported formats for CRL
stores:

openssl
has a directory in which hash. i files are stored, one CRL per file, and all CRLs
for the trust anchors whose subject distinguished name hashes to hash are read and
evaluated for each certificate issues by the CAs whose subject name hash matches
hash

OpenSSL in version 1 changes its subject name hashing algorithm, though, so that
for one trust anchor two hashes could be used, depending on the specific OpenSSL
version at hand. If OpenSSL version 1 or higher is used by fetch-crl and the
default mode is used, each CRL is written out twice, once for each possible hash
value. This mode in controlled by the opensslmode = { dual | single } configuration
option in the configuration file.

pem writes out the CRL in PEM (RFC 1421) format.

der writes out the CRL in binary under distinguished encoding rules

nss will use the crlutil from the Mozilla NSS tools to add or replace a CRL in the NSS
cert8.db database.

Each CRLs can be retrieved from one of several URLs. These URLs are listed by default in
the trust anchor meta-data: the .info file or the .crl_url file, as shipped with the trust
anchor. In the crl_url file, there is one URL per line; in the .info file, the crl_url
attribute is a semi-colon separated list of URLs. These URLs are then tried in order to
retrieve a fresh CRL. Once data has been successfully retrieved, this data is used as the
CRL if it passes verification, signature checking and expiration checks. Http, https, ftp
and file URLs are supported. If data for a CRL has been downloaded but this data fails any
of the subsequent checks (signature validation, freshness), the CRL data is discarded and
NO further URLs are tried for this CRL!

URLs can be pre-pended or post-pended to the default list via the configuration file. This
can be used to prefer a local mirror repository over any URLs shipped by the trust anchor
provider, without the need to modify the trust anchor metadata. By post-pending a URL, a
'last-resort' download location can be added in case the CA provided URLs cannot be used.
The pre- and post-pended URLS are subject to token expansion of the tokens @ALIAS@,
@ANCHORNAME@, and @R@, where R is the sequence number of the CRL on a per-trust anchor
basis.

Retrieved CRLs may be PEM (RFC1421) or DER encoded. They are automatically converted as
needed by fetch-crl, using the OpenSSL command-line tool.

Retrieving a CRL without having an accompanying CA root certificate in an OpenSSL-
accessible form (like @ALIAS@.0 or @ANCHORNAME@.@R@ will result in a verification
failures. The CA lookup directory and patterns can be configured via the configuration
file

TOKEN EXPANSION

       In  paths and name templates, tokens are expanded to allow a single pattern to be used for
       all  trust  anchors.  The  nametemplate_*,  catemplate,  prepend_url,   and   postpend_url
       configuration settings are subject to token expansion.

       The following tokens are recognised

       @ALIAS@
              The alias name of the trust anchor as defined in the info file. If there is no info
              file and the meta-data is retrieved from crl_url files, then the alias  is  set  to
              the basename (excluding the .crl_url suffix) of the filename of the trust anchor.

       @ANCHORNAME@
              The file name of the trust anchor, without any .info or .url_crl suffix.

       @R@    The  CRL sequence number, counting from 0. Note that most trust anchors only have a
              single CRL, with sequence number "0".

OPTIONS

-h --help
Show help text.

-l --infodir metadata-directory
The script will search this directory for files with the suffix '.info' or
'.crl_url'. Note: the CRL files to download must be in either PEM or DER format.

-o --out outputDirectory
Directory where to put the downloaded and processed CRLs. The directory to be used
as argument for this option is typically /etc/grid-security/certificates Default:
infodir (meta-data directory)

-a --agingtolerance hours
The maximum age of the locally downloaded CRL before download failures trigger
actual error messages. This error message suppression mechanism only works if the
CRL has been downloaded at least once and either the crl_url files are named after
the hash of the CRL issuer name, or a state directory is used to preserve state
across invocations.

Default: 24 hour aging tolerance

-q --quiet
Quiet mode (do not print information messages)

-r --randomwait s
Wait up to s seconds before starting the retrieval process(es).

-p --parallelism n
Do the retrieval for several trust anchors in parallel, with up to n processes
doing retrievals. At most n downloads will be active at any one time. Multiple CRLs
for the same trust anchor are still downloaded sequentially.

--inet6glue
Load the Net::INET6Glue module to enable IPv6 support in LWP.

--define key=value
Add definitions to the configuration at runtime. The key=value pair is appended to
the main section of the configuration, unless a colon is used in the key: then the
part before the colon is the config file section name, and the part thereafter the
key inside that section. To merely set a valueless option, set to to the null-
string "".

CONFIGURATION

       See http://wiki.nikhef.nl/grid/FetchCRL3 or the included example file for a description of
       the configuration options. The default location of the configuration file  is  /etc/fetch-
       crl.conf.   Supplementary  configuration  is  read  from  all files located in /etc/fetch-
       crl.d/, or the directory designated by the cfgdir directive, whose collated  contents  are
       added to the existing configuration data.

NOTES

       Defaults can be set in the fetch-crl system configuration file /etc/fetch-crl.conf.

DIAGNOSTICS

       Exit  status  is  normally 0; if an error occurs, exit status is 1 and diagnostics will be
       written to standard error.

LICENSE

       Licensed under the Apache License, Version 2.0 (the "License");

       http://www.apache.org/licenses/LICENSE-2.0

BUGS

       Although fetch-crl3 will install multiple CRLs in the CRL stores (called '.r0', '.r1',  or
       labelled  appropriately  in  an NSS store), if the number of CRLs decreases the left-overs
       are not automatically removed. So if the number of CRLs for a particular CA does down from
       n to n-1, the file '.rn' must be removed manually.