c-icap(8) ICAP filtering server


c-icap [ -f config-file ] [ -N ] [ -d debug-level ] [ -D ]


c-icap is an implementation of an ICAP server. It can be used with HTTP proxies that support the ICAP protocol. Most of the comercial HTTP proxies must support ICAP pcotocol.


-f config-file
Specify the configuration file
Do not run as daemon
-d level
Specify the debug level
Print debug info to stdout


The main configuration file

 In this file defined the types of files and the groups of file types.
By default c-icap writes its pid in this file. The path of this file can changed using the PidFile configuration parameter in the c-icap.conf file
The commands socket. This file used to send commands to the icap server from command line. For information about implemented commands look below in the "Implemented commands" sub-section


Implemented commands

Currently the following commands are implemented:
The c-icap will shutdown
The service will reread the config file without the need to stop and restart the c-icap server. The services will be reinitialized
This command causes c-icap to close and reopen the log files. This is very useful for log rotation.

Services and modules can define their own commands.


To reconfigure c-icap:

      echo -n "reconfigure" > /var/run/c-icap.ctl
To rotate access log:

      mv /var/log/c-icap/access.log /var/log/c-icap/access.log.1
      echo -n "relog" > /var/run/c-icap.ctl

Lookup tables

Lookup tables are simple read-only databases. A lookup table can defined in c-icap.conf file using the form:        type:path
where the type is the type of lookup table and path is the extra information required to use the table (e.g. file path). Currently the following lookup table types defined internally by c-icap:
Simple text file databases. The database records are stored in text files in the form:

 key[: value1, value2 ...]
example path definition:
Similar to file lookup tables but c-icap uses fast hashes for searching.
example path definition:
Similar to the file lookup tables but the keys are regular expressions in the form /regex/flags . For possible flags values please read 'Regex expressions' paragraph in this manual.
example regex lookup table data:
       /^[a-m].*/i: group1

       /^[n-z].*/i: group2
example path definition:

Regex expressions

The c-icap regex expressions have the form /regex_definition/flags where "flags" is one or more letters, its of them express a flag.
Common flags
g This flag forces the score multiplied by the number of regex
  expression matches. For example if the expression matches 5
  times and the devined score value is 10 then the final score
  will be 50.
i Do caseless matching
m Match-any-character operators don't match a newline
  and ^$ operators does not match newlines within data
If the module compiled using the pcre library the following flags can be used
s (PCRE_DOTALL) matches anything including NL
x (PCRE_EXTENDED) Ignore whitespace and # comments
A (PCRE_ANCHORED) Force pattern anchoring
D (PCRE_DOLLAR_ENDONLY) $ not to match newline at end
U (PCRE_UNGREEDY) Invert greediness of quantifiers
X (PCRE_EXTRA) PCRE extra features
u (PCRE_UTF8) Run in UTF-8 mode

Runtime information

Someone can retrieve runtime information using the info service. The information includes bytes received and transmited, active services, information about service usage and many other. The information provided in HTML and text format.


Retrieve runtime information from command line:
c-icap-client -i localhost -s "info?view=text" -req "a_url"




Tsantilas Christos