What's
new (in 2.5) The
WWW Counter program is continually being enhanced. Please check
this section periodically to see the latest enhancements and
bug fixes. Please look at the Section Features
for all the features.
A
new parameter cdf is added, to specify
countdown from date so that the difference between
two dates can be shown if you specify the target date witht
he parameter cdt.
(Jul-17-1999)
Fixed some memory related bugs. Modified the Commaize()
funtion, it had a memory free related bug. remote_ip var
had dangling memory read problem. All memory related bugs
were fund by Parasoft's insure++.
(May-26-1999)
The binary version of the current release for NT is available.
Please visit the NT binary page.
(May-25-1999)
Compositing
the counter on a base image had many bugs. All are fixed
I think. Now you can composite counter, clock or countdown
image on a base image (previously only counter image could
be composited). Left padding the counter while compositing
was not working either. The align keyword
had more values now, namely topleft, topcenter, topright,
midleft, midcenter, midright, bottomleft, bottomcenter and
bottomright. A new keyword offset
can be used with align to specify the
offset (in pixels) of the counter image from the edge of
the base image.
(May-16-1999)
The meaning of image parameter is changed.
Now this parameter is used for compositing the counter,
clock, date or countdown image. If no display
paramter is used, the default is to composite the counter
image.
(May-16-1999)
A new boolean keyword sdhms (show day
hr min sec) is added, so that only days in countdown can
be displayed.
(May-16-1999)
A new parameter display=version is
introduced to show the version of the counter. A command
line flag -version also can be used to find out the version
of the counter.
(May-16-1999)
Yes it includes the Buffer Overflow security fix (Fixed
on: Oct-17-1997 in Count 2.3).
This is a CGI
program to keep record of the raw hits of a web page. It generates
a GIF image of the number of hits and returns to the browser
as an in-lined image. The program also has a run-time option
not to show the digit images, this way the hits can be kept
without displaying it. The hits can be be monitored without
incrementing from a separate page as well. The program can
also can display time and date of any timezone. It has a option
to countdown to a specific date (past or future). Almost all
of the features are run-time options.
This program started as a fun-to-play-with CGI program but
due to enormous interest, feature request, input from thousands
of you, it has turned in to the most configurable hit counter
on the whole World Wide Web and it's free. The program
runs on almost all Known Unix platforms, Windows NT, OS/2,
VMS and Amiga.
Countdown to a specific date (past or future). Countdown
can be done in reference to local server time or any timezone
with the parameter timezone. Two
new keywords are added: display=countdown
and cdt=year;month;day;hr;min;sec. If
display=countdown is used and no cdt is specified, the default
countdown to Year 2000 is assumed. The current time and
date can be displayed below the countdown if the sfd=T
is used. Please look at the Options
section and FAQ Question# 28
for details. Also look at the Examples
section to see how it looks.
(new in this release)
Site admin can decide to count or ignore page reload via
a keyword ( count_reload) in configuration
file. If the site admin decides to count reload (count_reload=Yes),
then a user can choose to count or ignore reload with parameter
reload=T or F. Note, if the side admin
decided to ignore reload, then the user preference is ignored.
(new in this release)
The counter image can be composited with a base image to
a specific location. New keyword: xy=x;y
(Sub-image x and y co-ordinate). The parameter align
can be used to specify the width and height of the counter
image in the <img src= tag while calling the counter.
The implication is, if the counter is the first thing in
a large table, the browser will not have to wait to calculate
the width and height of the counter image before loading
the rest. Please look at the Examples
section to see how it works.
(new in this release)
The site admin can log the counter messages in the log file
or ignore the messages by specifying a keyword and value
(log_error_messages=Yes or No) in the configuration
file in section [options].
(new in this release)
The maximum number of digits the counter can count and display
can be very high. By default the maximum number of hits
can be (10^80)-1, which is a very large number (9999999999999999999999999999999999999999999 9999999999999999999999999999999999999),
that is if data is not edited by hand, practically it is
impossible to overflow the counter.
Wild card can be used in the IPs in ignore host block in
the config file. There is no limit for number of IPs (as
long as memory is not exhausted).
Wild card can be used in the hosts/IPs in the auth block
of the config file. There is no limit for number of hosts/IPs
(as long as memory is not exhausted).
The counter can count with image= parameter if df= parameter
is specified.
Count or ignore Consecutive reloading a page from the same
host a configurable option in the count.cfg file (used to
be a compile-time option). (Added on: Dec-13-1998).
"cache"
and expires" parameters can be used to change the caching
behavior of certain browsers.
Date in clock is Year 2000 safe. Note, you will not see
full year in the counter until the year 2000 arrives unless
you use the parameter fy, or specify YYYY
with the option dformat.
Uses image strip as well as individual digit images. Using
an image strip reduces disk i/o significantly, therefore,
it's faster. A program (mkstrip) is supplied to create an
image strip from individual digit images.
Comma can be displayed after every 3rd digit from right.
Any one color of the image can be changed on the fly.
Uses netmasks to mask out a range of hosts in the network
or the entire network.
Automatic datafile creation, strict mode, use of rgb color
database can be controlled from the cfg file at run time.
Any arbitrary GIF file can be displayed. Frame and other
attributes of the counter can be applied to the GIF file.
Count 2.0 is backward compatible with Count1.5's URL. One
thing to note, the keyword wxh has no meaning in
Count 2.0. It was used in Count 1.5 to specify digit dimensions.
In Count 2.0 it is not required, because the digit dimensions
are determined automatically. Therefore, you can use variable
width digit images in this version.
Reasonable default for all QUERY_STRING parameters.
The same program can be used to display time or date.
The time and date of any timezone in the world can be displayed.
The time can be displayed in 12 or in 24 hour format.
Supports digit images with variable width.
Counter can be displayed without incrementing (for monitoring
etc.)
A literal digit string can be displayed.
A random digit string can be displayed.
The color of the digits can be negated.
The counter can be rotated (only integral of 90 degrees,
90,180,270). The default rotation is 270 degrees.
An ornamental 3D frame can be wrapped around the
counter image with user defined thickness and color at run
time.
The frame and transparent color can be a name (e.g. red,green,pink
etc.). The color can be specified as a hex string, e.g.
ffffff, ff0000 etc. as well as RGB triplets as before.
Single program for any number of users for any number of
web pages.
Any color of the counter image can be made transparent
at run time.
Style of digits can be specified at run time.
Authorized host names can be in the configuration file.
Authorized hosts are those which can run the counter remotely.
Do not confuse this with visitors from certain hosts.
IP filtering through a configuration file at run time.
Any number of hosts can be ignored from counting. A netmask
can be used to filter out a specific range of hosts in a
network or to filter out the entire network. It's a good
idea to ignore your own host or entire domain. Gen-conf
program will let you create the configuration file interactively.
Data
file locking. Data file will not get clobbered by simultaneous
Count.cgi processes. NOTE, locking may not work if the counter's
datafile is on a NFS partition.
Maximum number of digits can be set or counter can be displayed
with exact number of digits at run time.
User will be able to specify a start-up counter value at
run time. This will take effect if the data file
does not exist. You will be prompted by the configuration
program if you want this feature or not.
If you do not want to display the counter but like
to keep the hits on your page, sh=0 can be defined in the
QUERY_STRING at run time. It will write a 1x1 transparent
GIF image to the browser but the counter in the data file
will be incremented properly. Digit Styles
(all platforms) The digits used in this program
can be individual GIF files or all the digits can be in
a single image strip. This gives you the flexibility of
using digits of your choice. If you have individual digit
images, they are named as zero.gif, one.gif,.... nine.gif,
colon.gif, am.gif, pm.gif, comma.gif, dash.gif, d.gif, h.gif,
m.gif and s.gif.If you have an image strip, the strip is
named as strip.gif. At run-time, the directory of the images
is simply used to specify a different style. Therefore,
a single program can display digits of various styles. Here
are the supplied digit styles. Some of the styles of digits
are supplied as a single image strip, while other are single
digit styles requiring the use of the istrip=F
option. Note the order of the digits (you will know about
it later).
Style A
designed by the author. D, H, M, S segment added by Andrew
Taylor
(digits/A/strip.gif)
Note:
in Unix, the .exe extension is not used to determine a executable.
You can call your program anything you like. So, if your server
is not on Unix, the name of the counter program will be Count.exe
instead of Count.cgi.
The
string after the ? mark is called the QUERY_STRING. Make
sure there are no newlines in the <img src= line and
no space in the QUERY_STRING. In df=sample.dat, df
means datafile and sample.dat is the counter datafile.
The counter stores the hits in this file. This datafile
is supplied.
The
counter program has lots of options, you can make it work
and look the way you desire. In the query string, you can
use the options described in the table below. The options
can be separated by a | or a &. You can use either one
or combination of both but I prefer to use & as some
browser may not like |. Here is an example:
These parameters can be used to change the image caching
behavior of certain web browsers.
The boolean value of cache tells the browser whether
to cache the image or not. The integer value of expires
specifies the cache expiration duration time in seconds.
If you specify cache=F, the browser will be hinted to
cache the image for the amount of seconds specified with
expires parameter. if cache=F and expires=0, then the
browser should not cache the image, that is whenever you
come back to the page, the counter or clock will be refreshed.
Use this feature with discretion as it may increase load
on your system. The expires parameter is meaningless
without cache=F, that means, if cache=T is specified,
expires parameter is ignored and the counter will not
generate any HTTP Expires header. This is the default
behavior. The valid values for the boolean parameter cache
is Y,N,F,T 1 or 0. The valid integer range of the expires
parameter is between 0 and 604800 (7 days).
Note, these parameters will work with browsers that
support the HTTP Expires header as specified in HTTP
specification. By default, most web browsers cache the
image received from the counter. That means, if someone
visits your page and comes back after a while, the counter
or clock does not get refreshed.
Count page reload if the site admin configured the counter
to support it.
(Added on: Dec-05-1998)
If the site admin configured the counter to count reload,
users can choose to count reload (default) or ignore reload.
The site admin allows count reloading by yes, 1 or true
in the [options] section of the configuration
file with the keyword count_reload. Note, if the admin
decided to ignore reload count (count_reload=No), user
preference is ignored. The valid values for the Boolean
parameter reload are Y, N, T, F, 1 or 0.
reload=T
Count reload if site admin configured to so.
The parameter cdt specifies the countdown target date.
The valid values for this parameter is 6 integers separated
by semicolon. The first integer specifies the year, for
example: 2000. The month starts at 1 (January). The first
day is 1. Note: in Unix systems, the year can not be less
than 1970 as Unix epoch starts starts at 00:00:00 on January
1, 1970, Coordinated Universal Time (UTC). The range of
hr is 0 to 23. The range of min is 0 to 59 and the range
of sec is 0 to 59. To count down to Year 2000, the parameter
will be: cdt=2000;1;1;0;0;0. If you do not specify any
Timezone with the parameter timezone,
the countdown will be calculated from the web server time.
For example if you like to show the countdown from GMT,
specify timezone as: timezone=GMT+0000.
The parameter cdf specifies the countdown from
date. The default is to calculate from the current local
time or local time of a specific timezone if the parameter
timezone is specified. The valid values for this
parameter is 6 integers separated by semicolon. The first
integer specifies the year, for example: 1999. The month
starts at 1 (January). The first day is 1. Note: in Unix
systems, the year can not be less than 1970 as Unix epoch
starts starts at 00:00:00 on January 1, 1970, Coordinated
Universal Time (UTC). The range of hr is 0 to 23. The
range of min is 0 to 59 and the range of sec is 0 to 59.
This parameter affects how the countdown is displayed.
The valid values for the Boolean parameter sdhms are Y,
N, T, F, 1 or 0. By defualt, the value for this parameter
is True, that means the countdown is shows as Day, Hour,
Min and Sec. If you just want to show the countdown days,
specify F as the value.
The parameter sfd shows the from date below the countdown.
The from date is the time when the program is executed.
The time in date is always in 24 hr format. If you use
the parameter timezone, the timezone
offset will be shown at the end of time. It may be necessary
to see this date to make sure that the Counter program
actually ran and the browser is not loading the image
from cache. Use cache=F&expires=0
to make sure that browser does not cache the image. The
valid values for the Boolean parameter sfd are Y, N, T,
F, 1 or 0.
The valid values for X is: counter, clock,
date, countdown, image or version.
If the value is countdown and if the countdown time is
not specified with parameter cdt, the
countdown to year 2000 is assumed. See also: cdt.
Note: If you specify display=image and if you specify
a datafile with df parameter and if
incr is true, then counter will be
incremented in the datafile. This will help some people
who do not like to show the counter, instead they can
show an image. You can use incr=F
from another page to monitor the counter.
The parameter timezone= is only significant with display=clock,
display=date or display=countdown
Use this parameter if you want to display time or date
of another timezone or calculate countdown in reference
to a timezone to a target date. The timezone must be specified
with a negative or positive four digit offset from GMT,
for example: timezone=GMT-0500 or timezone=GMT+0000 or
timezone=GMT+0530. The routine to display time of various
timezones are written in a generic way. Therefore, the
unix machines will not be aware of daylight saving time
because of the way the routine is written. For example,
if daylight saving time is on, to display time of NY,
the timezone will be timezone=GMT-0500 instead of timezone=GMT-0400.
If the clock displays your local time wrong, specify
your timezone with that parameter in order to display
the correct time.
This parameter is only significant with display=date.
The valid value for the string parameter X is any combination
of MMDDYY (Month-Day-Year). For example, dformat=ddmmyy,
dformat=YYMMDD. To show the full year in the display instead
of two digit year specify YYYY instead of YY, for example
dformat=MMDDYYYY. To show full year you can also use the
parameter fy.
Show the full year (fy) in the date instead of only two
digit year.
This boolean parameter indicates whether to show all the
year digits instead of default two digits in the date.
By the way the program will display all the year digits
by default from Year 2000. The valid values for the boolean
parameter fy are Y,N,T,F,1 or 0. See also:
dformat.
The boolean value of istrip specifies whether to use image
strip or not. If you specify istrip=F, the program will
look for the individual digit image files in the digits/style
directory. The valid values for the Boolean parameter
istrip are Y, N, T, F, 1 or 0.
Specifies the color of the frame in RGB (red/green/blue)
format. Each color component, R, G, and B is specified
as a value between 0 and 255. If you use ft= without a
frgb= param, the default color is used.
If you specify a frgb= without a ft=, then the frame
thickness defaults to 5. All the examples show ft=5.
The color can be specified as hex string or a name.
Do not use a # before the hex string as Netscape. For
example, if you want to specify white in hex, use frgb=ffffff.
You also can use a color name (e.g. frgb=blue) if the
counter is configured to do so (look at the cfg file).
Look at the
color name mapping database for some hints about
color name database.
You can specify if your counter image will have a transparent
color with the Boolean B. So tr=Y means there will be
a transparent color. It does not matter if the GIF files
used for the digits are "transparent"; you must specify
explicitly which color to make transparent. If you specify
a trgb=, then you do not need to specify tr=Y. If you
specify tr=Y and do not specify trgb=, then the default
color black will be transparent. The valid values for
B are Y, N, T, F, 1, or 0.
Specifies the color to be made transparent in RGB (red/green/blue)
format. Each color component, R, G, and B is specified
as a value between 0 and 255. If you use tr= without a
trgb= param, the default color is used. The color can
be specified as hex string or a name. Do not use a # before
the hex string as Netscape. For example, if you want to
specify white in hex, use trgb=ffffff. You also can use
a color name (e.g. trgb=blue) if the counter is configured
to do so (look at the cfg file). Look at the
color name mapping database for some hints about color
name database. If you use trgb= then tr=Y is not needed.
Defines maximum number of digits to display. Any value
between 5 and 80 inclusive are permitted. Padding with
leading zeros is automatically done for you; longer counts
are truncated to the given X.
Turn padding on/off in conjunction with md= setting. It
also affects padding hour in clock. Valid values for the
Boolean parameter B are Y, N, T, F, 1, or 0.
Denotes directory of a specific styles of digits. Four
styles of digits are supplied. They are kept at the directories
A,B,C and D respectively. Visit the digit
mania page for other styles of digits.
You can display any GIF image specified with this parameter.
The location of this file is determined by the dd= parameter.
Note that no path in the GIF file is allowed. All attributes
of the counter apply to the image. This parameter is used
for compositing counter image with the GIF image. The
default alignment is top-center and the default offset
is 2 pixels from the top of the GIF image. If you want
to composite clock, date or contdown, specify so with
the display paramter.
The boolean value of parameter comma specifies whether
to display comma after every 3rd digit from right. If
you use this parameter as true, the left padding with
zeros will be turned off.
Change a color of the image to a target color on the fly.
Any one color of the image can be changed to a different
color on the fly. srgb stands for source color, that is
the color to change. prgb stands for pen color, that is
the target color. The values for srgb and prgb can be
colon separated color components (e.g, srgb=255;0;0),
a hex value (e.g. srgb=ff0000) or a color name (e.g. srgb=red).
The color name can be used if you configured the counter
to do so (look at the cfg file).
This parameter is usually used to change the default green
color to cyan. That is if you specify chcolor=T, and you
want to change green to cyan, then you do not need to
specify srgb and prgb parameters. 1x1 GIF is displayed.
The valid values for the Boolean parameter B are Y, N,
T, F, 1, or 0
This parameter is used to set the initial value of the
counter to some number X. This is only valid if you decided
to allow automatic datafile creation. It is a bad practice
to allow automatic datafile creation, however it makes
site maintaining easier. The automatic datafile creation
option is specified in configuration file and can be changed
at run time. Note that this parameter has no effect if
the datafile already exists. If you want to change the
counter value in a existing datafile, hand edit the file.
The minimum value for st is 1.
Used to turn display of digits on or off according to
the Boolean B. When sh=T, counter will be displayed and
incremented, this is the default behavior.
If sh=F no digits will show, but the counter will still
increment; instead of digits a transparent 1x1 GIF is
displayed. The valid values for the Boolean parameter
B are Y, N, T, F, 1, or 0
Specifies the name of the file for storing the count in.
The file must be allocated to you as was mentioned in
the "Authorizations" section above. You can use df=random
to display a random number.
One special use of the parameter is df=RANDOM. This
returns a random number using the fractional portion
of the host's time of day clock as a seed for the generator.
Unlike all other WWWcounter parameters, the file name
provided is case-sensitive, except for the value random.
Or Random, or rANDOM, etc.
Makes it possible to display the current count without
incrementing the count. This can be used to examine the
count for reporting or other purposes without adding to
the count. Valid values for the Boolean parameter B are
Y, N, T, F, 1, or 0.
Makes it possible to negate the color of the counter digits.
Note that the Frame is exempted from negating. Valid values
for the Boolean parameter B are Y, N, T, F, 1, or 0.
Makes it possible to rotate the counter image X degrees.
The possible values of X are 90, 180, 270 and 360. Note
360 is meaningless as the counter will come back to the
original 0 degrees. Note:
Microsoft MS Explorer interprets °rees as the degree
character (it's gotta be a bug in IE), so use angle to
be safe.
degrees=270
With rotate=Y and without degrees=X rotate 270 degrees clockwise
The Boolean value B turns on or off rotating. If you use
degrees= setting, rotate is not needed. Valid values for
the Boolean parameter B are Y, N, T, F, 1, or 0.
composite the counter image to a base image at the location
x,y
When a base image is specified with image
parameter, the parameter xy can be used to composite the
counter image on the base image at location x,y. x is
positive towards right and y is positive downward. The
co-ordinate of the upper left corner of the base image
is 0,0). See also: align.
composite the counter/ clock/ countdown image with a base
image and align the counter image.
This option can be used to composite the counter on a
base image (specified with image
with known width and height. This way, you will be able
specify the width and height of the counter image in the
<img src= tag while calling the counter. The implication
is, if the counter is the first thing in a large table,
the browser will not have to wait to calculate the width
and height of the counter image before loading the rest.
The valid value for the parameter align is topleft,
topcenter, topright, midleft, midright,
midcenter, bottomleft, bottomcenter
and bottomright. The parameter offset
can be used to specify the offset in pixels from the edge
of the base image. Note: xy parameter
has higher precedence than align. Therefore, if both xy
and align is specified xy will take the precedence. See
also: xy.
Offset of the counter image in pixels from the edge of
the base image while compositing the counter with an image.
The parameter offset is used with parameter align
to specify the offset of the counter image in pixels from
the edge of the base image while compositing the counter/clock
image with an base image. If align=topleft, the the offset
is counted from the top and left edge of the base image.
If align=topcenter, the offset is counted from the top
edge of the base image. If align=topright, the offset
is counted from the top and right edge of the base image.
If align=midleft, offset is counted from the left edge
of the base image. If align=midcenter, offset is ignored.
If align=midright, offset is counted from the right edge
of the base image. If align=bottomleft, offset is counted
from the left and bottom edge of the base image. If align=bottomcenter,
offset is counted from bottom edge of the base image.
If align=bottomright, offset is counted from the right
and bottom edge of the base image. The valid value for
the paramter N is a positive integer. See also: xy.
offset=2
The
count.cfg file contains the runtime configuration information
for the Count program. The file consists of sections and
parameters. A section begins with the name of the section
in square brackets and continues until the next section
begins. The sections contain parameters of the form keyword=value
or just keyword one in each line. The file is line-based,
that is, each newline-terminated line represents either
a comment, a section name or a parameter. The section
and the parameter names are not case sensitive. A sample
configuration file is shown below:
###-----------------------------------------------------------------------
### configuration file for Count 2.5
### Automatically generated from user input by the script Gen-conf
### created on: Sun Jan 3 18:15:01 EST 1999
### Note: Configuration file format for Count 2.5 is different than
### older versions. -- mm
### The format of the file is described below:
### - Any line starts with # or ; is considered comment and ignored.
### - A section in the file is inside left and right bracket.
### - Each section has parameters below the section.
###
### Please read the Configuration section in the counter webpage for details.
### The official counter homepage is at URL:
### http://www.fccc.edu/users/muquit/Count.html
###----------------------------------------------------------------------
[version]
2.5
##-- options section
; If auto_file_creation=Yes, then the users can create data files. It IS
; dangerous to set this option to Yes.
#
; strict_mode=Yes or No. Run the program in strict mode or not. It's a good
; idea to set this option to Yes.
#
; allow_rgb_database=Yes or No. Convenient to use because colorname e.g., red,
; gold etc can be used instead of rgb components of the color, however it is
; very inefficient to lookup. If your site is busy, set this option to No.
#
; count_reload=Yes or No. It is a good idea to set this option to No. But
; you've to set this option to Yes if you are running a proxy server.
; Normally set this to Yes.
#
; log_error_messages=Yes or No. If your site is extremely busy and if the
; counter generates lots of logs, set this option to No. Normally set this
; option to Yes.
#
; show_error_messages_to_browsers=Yes or No. Set this option to No if you're
; concerned with privacy and you're sure that the counter works perfectly.
; If you set this option to No, you will not see error messages.
[options]
auto_file_creation=No
strict_mode=Yes
allow_rgb_database=Yes
count_reload=No
log_error_messages=Yes
show_error_messages_to_browsers=Yes
; You can specify IP address of the hosts you want to ignore from counting.
; netmasks can be used to ignore a entire network or a specificrange of
; hosts in the network. Read the counter documentation to know about
; netmasks. Wild card can be used as well. one item per line.
;
[ignore IPs]
;
; All possible names and IP addresses by which your host can be referred.
; These hosts can access the counter remotely or locally. Host running
; the http server must exist here. Wild card can be used. one item per line.
;
[authorized]
*.bar.com
abcd.foo.com
abcd
131.249.1.100
www.foo.com
www
test.counter.com
The
config file is parsed each time the counter program gets
accessed. Therefore, smaller the file, the better the
performance. If you have thousands of entries in [ignore
IPs] or [authorized] section, you'll notice performance
degradation. Try using wild cards if possible.
As
of version Count version 2.4, referrer host names will
be looked up in DNS if the program is compiled with the
USE_DNS macro defined in src/Makefile. This allows you
to list wild-card IP address ranges in [authorized] section
of the config file. This feature can reduce a 200 line
[authorized] section down to a single line. Without USE_DNS,
the host name as sent by the browser's HTTP_REFERER header
must be listed EXACTLY.
You
can take an existing config file and modify it or use
the program Gen-conf to create one. Try to keep comments in the file to a minimum.
Note, [ignore ips] section only contains IP addresses,
IP address and netmask or wild carded IP addresses. Never
use host names in this section, they will be ignored.
Netmasks can be used to get finer control to ignore a
very specific range of hosts. Read the section How
to use netmasks at [ignore IPs] section if you have
specific need to ignore a range of hosts. Otherwise, use
wild cards and be happy. The [authorized] section contains
all the names and IP addresses of the hosts allowed to
execute the counter remotely or locally. The name and
IP of the host running the web server must be at this
section.
`Host ignore' block contains one or more lines with
IP addresses of hosts that will be ignored for counter
updates.
New feature in this release is possibility to mask off
groups of hosts (subnetworks) defined by corresponding
network / netmask pairs. This can be useful if we wish
to exclude accesses from the hosts on our campus or
hosts of people developing the pages.
To accomplish this, each line in host ignore block can
take two arguments. If second argument is present, first
is assumed to be network address and second the netmask.
If only one argument is present, it is take
