Script help needed please
Jack L. Stone
The above is typical of the servers in use, and with csh shells employed,
plus IPFW.
My apologies for the length of this question, but the background seems
necessary as brief as I can make it so the question makes sense.
The problem:
We have several servers that provide online reading of Technical articles
and each have several hundred MB to a GB of content.
When we started providing the articles 6-7 years ago, folks used browsers
to read the articles. Now, the trend has become a more lazy approach and
there is an increasing use of those download utilities which can be left
unattended to download entire web sites taking several hours to do so.
Multiply this by a number of similar downloads and there goes the
bandwidth, denying those other normal online readers the speed needed for
loading and browsing in the manner intended. Several hundred will be
reading at a time and several 1000 daily.
Further, those download utilities do not discriminate on the files
downloaded unless the user sets them to exclude certain types of files they
don't need for the articles. All or most don't bother to set the
parameters. They just turn them loose and go about their day. Essentially a
DoS for normal readers who notice the slowdown, but not with malice.
This method downloads a tremendous amount of unnecessary content. Some
downloaders have been contacted to stop (if we spot an email address from a
login) and in response they simply weren't aware of the problems they were
making and agreed to at least spread downloads over longer periods of time.
I can live with that.
A possible solution?
Now, my question: Is it possible to write a script that can constantly scan
the Apache logs to look for certain footprints of those downloaders,
perhaps the names, like "HTTRACK", being one I see a lot. Whenever I see
one of those sessions, I have been able to abort them by adding a rule to
the firewall to deny the IP address access to the server. This aborts the
downloading, but have seen the attempts constantly continue for a day or
two, confirming unattended downloads.
Thus, if the script could spot an "offender" and then perhaps make use of
the firewall to add a rule containing the offender's IP address and then
flush to reset the firewall, this would at least abort the download and
free up the bandwidth (I already have a script that restarts the firewall).
Is this possible and how would I go about it....???
Many thanks for any ideas on this!
Best regards,
Jack L. Stone,
Administrator
SageOne Net
http://www.sage-one.net
jack...@sage-one.net
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Jez Hancock
> Server Version: Apache/1.3.27 (Unix) FrontPage/5.0.2.2510 PHP/4.3.1
> The above is typical of the servers in use, and with csh shells employed,
> plus IPFW.
>
> My apologies for the length of this question, but the background seems
> necessary as brief as I can make it so the question makes sense.
>
> The problem:
> We have several servers that provide online reading of Technical articles
> and each have several hundred MB to a GB of content.
>
> When we started providing the articles 6-7 years ago, folks used browsers
> to read the articles. Now, the trend has become a more lazy approach and
> there is an increasing use of those download utilities which can be left
> unattended to download entire web sites taking several hours to do so.
> Multiply this by a number of similar downloads and there goes the
> bandwidth, denying those other normal online readers the speed needed for
> loading and browsing in the manner intended. Several hundred will be
> reading at a time and several 1000 daily.
There is no easy solution to this, but one avenue might be to look at
bandwidth throttling in an apache module.
One that I've used before is mod_throttle which is in the ports:
/usr/ports/www/mod_throttle
which allows you to throttle users by ip address to a certain number of
documents and/or up to a certain transfer limit. IIRC it's fairly
limited though in that you can only apply per IP limits to _every_
virtual host - ie in the global httpd.conf context.
A more finegrained solution (from what I've read, haven't tried it) is
mod_bwshare - this one isn't in the ports but can be found here:
http://www.topology.org/src/bwshare/
this module overcomes some of the shortfalls of mod_throttle and allows
you to specify finer granularity over who consumes how much bandwidth
over what time period.
> Now, my question: Is it possible to write a script that can constantly scan
> the Apache logs to look for certain footprints of those downloaders,
> perhaps the names, like "HTTRACK", being one I see a lot. Whenever I see
> one of those sessions, I have been able to abort them by adding a rule to
> the firewall to deny the IP address access to the server. This aborts the
> downloading, but have seen the attempts constantly continue for a day or
> two, confirming unattended downloads.
>
> Thus, if the script could spot an "offender" and then perhaps make use of
> the firewall to add a rule containing the offender's IP address and then
> flush to reset the firewall, this would at least abort the download and
> free up the bandwidth (I already have a script that restarts the firewall).
>
> Is this possible and how would I go about it....???
If you really wanted to go down this route then I found a script someone
wrote a while back to find 'rude robots' from a httpd logfile which you
could perhaps adapt to do dynamic filtering in conjunction with your
firewall:
http://stein.cshl.org/~lstein/talks/perl_conference/cute_tricks/log9.html
If you have any success let me know.
--
Jez
Michael Conlen
You can setup Apache to deny access to people using that browser. The
catch is that it's easy to work around it by changing the browser
string. If they are that desperate to do this after you deny access to
people using HTTRACK or other clients you can place a link that no human
would access that runs a CGI that runs the firewall rule to deny them
access. You probably want it to return some data and wait a bit so the
user can't figure out easily what URL is killing their access.
You can also put on your website that users are not allowed to use the
site using non interactive browsers. Then when you find them you send a
nasty gram to their ISP and notify them that continued abuse could be a
crime under the Computer Fraud and Abuse Act (if you and they are in the
US) and let their ISP take care of it.
--
Michael Conlen
Jack L. Stone wrote:
>Server Version: Apache/1.3.27 (Unix) FrontPage/5.0.2.2510 PHP/4.3.1
>The above is typical of the servers in use, and with csh shells employed,
>plus IPFW.
>
>My apologies for the length of this question, but the background seems
>necessary as brief as I can make it so the question makes sense.
>
>The problem:
>We have several servers that provide online reading of Technical articles
>and each have several hundred MB to a GB of content.
>
>When we started providing the articles 6-7 years ago, folks used browsers
>to read the articles. Now, the trend has become a more lazy approach and
>there is an increasing use of those download utilities which can be left
>unattended to download entire web sites taking several hours to do so.
>Multiply this by a number of similar downloads and there goes the
>bandwidth, denying those other normal online readers the speed needed for
>loading and browsing in the manner intended. Several hundred will be
>reading at a time and several 1000 daily.
>
>Further, those download utilities do not discriminate on the files
>downloaded unless the user sets them to exclude certain types of files they
>don't need for the articles. All or most don't bother to set the
>parameters. They just turn them loose and go about their day. Essentially a
>DoS for normal readers who notice the slowdown, but not with malice.
>
>This method downloads a tremendous amount of unnecessary content. Some
>downloaders have been contacted to stop (if we spot an email address from a
>login) and in response they simply weren't aware of the problems they were
>making and agreed to at least spread downloads over longer periods of time.
>I can live with that.
>
>A possible solution?
>Now, my question: Is it possible to write a script that can constantly scan
>the Apache logs to look for certain footprints of those downloaders,
>perhaps the names, like "HTTRACK", being one I see a lot. Whenever I see
>one of those sessions, I have been able to abort them by adding a rule to
>the firewall to deny the IP address access to the server. This aborts the
>downloading, but have seen the attempts constantly continue for a day or
>two, confirming unattended downloads.
>
>Thus, if the script could spot an "offender" and then perhaps make use of
>the firewall to add a rule containing the offender's IP address and then
>flush to reset the firewall, this would at least abort the download and
>free up the bandwidth (I already have a script that restarts the firewall).
>
>Is this possible and how would I go about it....???
>
>Many thanks for any ideas on this!
>
>Best regards,
>Jack L. Stone,
>Administrator
>
>SageOne Net
>http://www.sage-one.net
>jack...@sage-one.net
Jack L. Stone
>On Thu, Aug 14, 2003 at 08:49:49AM -0500, Jack L. Stone wrote:
>> Server Version: Apache/1.3.27 (Unix) FrontPage/5.0.2.2510 PHP/4.3.1
>> The above is typical of the servers in use, and with csh shells employed,
>> plus IPFW.
>>
>> My apologies for the length of this question, but the background seems
>> necessary as brief as I can make it so the question makes sense.
>>
>> The problem:
>> We have several servers that provide online reading of Technical articles
>> and each have several hundred MB to a GB of content.
>>
>> When we started providing the articles 6-7 years ago, folks used browsers
>> to read the articles. Now, the trend has become a more lazy approach and
>> there is an increasing use of those download utilities which can be left
>> unattended to download entire web sites taking several hours to do so.
>> Multiply this by a number of similar downloads and there goes the
>> bandwidth, denying those other normal online readers the speed needed for
>> loading and browsing in the manner intended. Several hundred will be
>> reading at a time and several 1000 daily.
>There is no easy solution to this, but one avenue might be to look at
>bandwidth throttling in an apache module.
>
>One that I've used before is mod_throttle which is in the ports:
>
>/usr/ports/www/mod_throttle
>
>which allows you to throttle users by ip address to a certain number of
>documents and/or up to a certain transfer limit. IIRC it's fairly
>limited though in that you can only apply per IP limits to _every_
>virtual host - ie in the global httpd.conf context.
>
>A more finegrained solution (from what I've read, haven't tried it) is
>mod_bwshare - this one isn't in the ports but can be found here:
>
>http://www.topology.org/src/bwshare/
>
>this module overcomes some of the shortfalls of mod_throttle and allows
>you to specify finer granularity over who consumes how much bandwidth
>over what time period.
>
>> the Apache logs to look for certain footprints of those downloaders,
>> perhaps the names, like "HTTRACK", being one I see a lot. Whenever I see
>> one of those sessions, I have been able to abort them by adding a rule to
>> the firewall to deny the IP address access to the server. This aborts the
>> downloading, but have seen the attempts constantly continue for a day or
>> two, confirming unattended downloads.
>>
>> Thus, if the script could spot an "offender" and then perhaps make use of
>> the firewall to add a rule containing the offender's IP address and then
>> flush to reset the firewall, this would at least abort the download and
>> free up the bandwidth (I already have a script that restarts the firewall).
>>
>> Is this possible and how would I go about it....???
>wrote a while back to find 'rude robots' from a httpd logfile which you
>could perhaps adapt to do dynamic filtering in conjunction with your
>firewall:
>
>http://stein.cshl.org/~lstein/talks/perl_conference/cute_tricks/log9.html
>
>If you have any success let me know.
>
>--
>Jez
>
Interesting. Looks like a step in the right direction. Will weigh this one
along the possibilities.
Many thanks...!
Alexander Haderer
>...
>When we started providing the articles 6-7 years ago, folks used browsers
>to read the articles. Now, the trend has become a more lazy approach and
>there is an increasing use of those download utilities which can be left
>unattended to download entire web sites taking several hours to do so.
>Multiply this by a number of similar downloads and there goes the
>bandwidth, denying those other normal online readers the speed needed for
>loading and browsing in the manner intended. Several hundred will be
>reading at a time and several 1000 daily.
>
>A possible solution?
What comes to my mind:
- Offer zip/tar.gz archives via an ftp server to your customers.
- allow customer's server to mirror your ftp-server
- probably: setup a mailing list to inform your customers about changes/updates
Of course you can additionally install some bandwith limitation stuff. (But
I don't know one, sorry).
Alexander
Jack L. Stone
>At 03:44 PM 8.14.2003 +0100, Jez Hancock wrote:
>>On Thu, Aug 14, 2003 at 08:49:49AM -0500, Jack L. Stone wrote:
>>> Server Version: Apache/1.3.27 (Unix) FrontPage/5.0.2.2510 PHP/4.3.1
>>> The above is typical of the servers in use, and with csh shells employed,
>>> plus IPFW.
>>>
>>> My apologies for the length of this question, but the background seems
>>> necessary as brief as I can make it so the question makes sense.
>>>
>>> The problem:
>>> We have several servers that provide online reading of Technical articles
>>> and each have several hundred MB to a GB of content.
>>>
>>> to read the articles. Now, the trend has become a more lazy approach and
>>> there is an increasing use of those download utilities which can be left
>>> unattended to download entire web sites taking several hours to do so.
>>> Multiply this by a number of similar downloads and there goes the
>>> bandwidth, denying those other normal online readers the speed needed for
>>> loading and browsing in the manner intended. Several hundred will be
>>> reading at a time and several 1000 daily.
>
>Many thanks...!
>
>Best regards,
>Jack L. Stone,
>Administrator
>
Want to thank all that replied. Since this post for help, I noticed another
post about a log monitoring program "Swatch" which resides in
/usr/ports/security/swatch.
I did a test install of Swatch and was quite excited about its ability as
simple as the program is. It worked immediately to send me alarm(s)
(adjustable) that one of the download utilities "HTTrack" was on the
attack. And, I do mean bells went off and emails were shot to me
immediately for each attack session (not really attacks of course, but does
suck out the server's energy).
Now, I at least have a tool that will keep a vigilent watch for me and I
don't have to wait until the server slows down to realize we have a problem.
Now2 -- if I can just find a way to connect the alarm from Swatch to
somehow abort the session(s). This little program does indeed have some
more line commands that can be entered into the config file. Maybe I am 75%
of the way along.....
Best regards,
Jack L. Stone,
Administrator
SageOne Net
http://www.sage-one.net
jack...@sage-one.net