Re: find out who accessed a file

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On Sat, January 24, 2015 11:27 am, Tim Dunphy wrote:
> Hey guys,
>
> Unless you're using auditd (or a similar service) to watch the file,
> no.  You could probably use the logs and `last` to see who was logged
> in at the time and make a guess.
>
>
>
> Also, you can look into shell history files (though that might be cleaned
> by users). Admin is allowed to do that when investigates incident.
> One more thing: if "access" constitutes execution of that file, you can
> use lastcomm (if process accounting is enabled on the system). This only
> tells you the command name (not its arguments....) - so if your file is
> command and you are interested who executed it and when lastcomm is your
> friend.
>
>
>
> Thanks for these suggestions! But one thing that I should have mentioned
> is
> that it's not a user logging into the system that's accessing that file.
> It's actually a php script that's trying to read from it. The script is
> failing to pull information from the file, and failing. It's trying to
> access the file as a user account that exists on the system . And we're
> seeing 'access denied' messages in the apache error logs.

If it is php script that runs by web server then the user web server
daemon runs as will be the one who needs access. On centos with apache web
server it is usually unprivileged user "apache (as apache starts as
privileges user root to read certificate secret key, then drops
privileges). You need to have file in question be readable as apache. Easy
debugging would be: get root shell, then

su - apache
cat /path/to/file/in/question

(assuming it is ASCII text file). One other thing I would try: disable
selinux, and see if that lets apache read file, e.g.:

setenforce 0

Also: posting relevant "access denied" lines from web server logs may help
other to spot something.

Valeri

>
> An important difference, that I should have mentioned. Sorry about that!
> So
> I'm thinking if I can watch the file using auditd, I can see attempts by
> the user the script runs as in accessing the file?
>
> Thanks
> Tim
>
> On Fri, Jan 23, 2015 at 4:23 PM, Valeri Galtsev
> <galtsev@xxxxxxxxxxxxxxxxx>
> wrote:
>
>>
>> On Fri, January 23, 2015 3:13 pm, Jonathan Billings wrote:
>> > On Fri, Jan 23, 2015 at 03:50:44PM -0500, Tim Dunphy wrote:
>> >>  Is there any way to find out the last user to access a file on a
>> CentOS
>> >> 6.5 system?
>> >
>> > Unless you're using auditd (or a similar service) to watch the file,
>> > no.  You could probably use the logs and `last` to see who was logged
>> > in at the time and make a guess.
>> >
>>
>> Also, you can look into shell history files (though that might be
>> cleaned
>> by users). Admin is allowed to do that when investigates incident.
>>
>> One more thing: if "access" constitutes execution of that file, you can
>> use lastcomm (if process accounting is enabled on the system). This only
>> tells you the command name (not its arguments....) - so if your file is
>> command and you are interested who executed it and when lastcomm is your
>> friend.
>>
>> Good luck!
>>
>> Valeri
>>
>> ++++++++++++++++++++++++++++++++++++++++
>> Valeri Galtsev
>> Sr System Administrator
>> Department of Astronomy and Astrophysics
>> Kavli Institute for Cosmological Physics
>> University of Chicago
>> Phone: 773-702-4247
>> ++++++++++++++++++++++++++++++++++++++++
>> _______________________________________________
>> CentOS mailing list
>> CentOS@xxxxxxxxxx
>> http://lists.centos.org/mailman/listinfo/centos
>>
>
>
>
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>


++++++++++++++++++++++++++++++++++++++++
Valeri Galtsev
Sr System Administrator
Department of Astronomy and Astrophysics
Kavli Institute for Cosmological Physics
University of Chicago
Phone: 773-702-4247
++++++++++++++++++++++++++++++++++++++++
_______________________________________________
CentOS mailing list
CentOS@xxxxxxxxxx
http://lists.centos.org/mailman/listinfo/centos




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