From mboxrd@z Thu Jan 1 00:00:00 1970 From: Steve Grubb Subject: Re: Excluding audit for BIND daemon Date: Fri, 22 Sep 2017 12:47:00 -0400 Message-ID: <12657632.xMCL0O33bu@x2> References: Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: linux-audit-bounces@redhat.com Errors-To: linux-audit-bounces@redhat.com To: linux-audit@redhat.com List-Id: linux-audit@redhat.com Hello, On Friday, September 22, 2017 1:09:19 AM EDT Rituraj Buddhisagar wrote: > I have a DNS server for which the auditd was generating lot of system calls > and flooding the logs. > Due to this the server was under heavy memory usage as audisp-remote was > hogging the memory. The log output for audisp-remote showed that the > syscall was 49. Then I got to know from ausyscall command that the call > number 49 corresponds to bind. Hence I have *excluded* the call to "bind". > > I have put in below line in the /etc/audit/audit.rules > > *-a exclude,always -S 49* > > I have put the above line before section 10.2.2 which says "Feel free to > add below this line" (please note I am running Ubuntu 14.04 but I suppose > auditd implementation is same across board) . Also know that the rules are looked at from top to bottom with the first match winning. So, you would want this rule above whatever is causing events. > After the exclusion - I no more see the syscall=49 line in > /var/log/audit/audit.rules. So thats a success of sorts! > > *Probem/Issue/Query now*: After the exclusion, I do see audit events for > cron , sudo etc. But I do not see a call for "vi" file open mode etc. I'd need to see the rules to figure out what's wrong, but I have some hints below... > *Background:* > > log output earlier which was flooding the logs and giving message " *dns1 > audisp-remote: message repeated 6613 times: [ queue is full - dropping > event"* > > *log:* > *type=SYSCALL msg=audit(1506025977.586:46629194): arch=c000003e syscall=49 > success=yes exit=0 a0=3 a1=7ffe540ecf20 a2=c a3=0 items=0 ppid=22337 > pid=22338 auid=4294967295 uid=0 gid=0 euid=0 suid=0 fsuid=0 egid=0 sgid=0 > fsgid=0 tty=(none) ses=4294967295 comm="audisp-remote" > exe="/sbin/audisp-remote" key="root_action"* The main question is what is the root_action rule(s)? Normally we add a auid!=4294967295 to prevent daemons from causing events. Typically when it's desired to get root events, its means that you want to target _people_ running as root rather than normal system activity. > root@dns1:/tmp# ausyscall 49 > *bind* > > I do see audit events for cron , sudo etc. But I do not see a call for "vi" > file open mode etc. > > Observation: I open file /etc/audit/audit.rules in vi editor and then close > it. Audit log does not show syscall=2 If you were wanting to record writes to that, you would use a rule like this: -w /etc/audit/ -p wa > Earlier I used to see below output in logs, but I am not sure that was for > which file opened in vi editor. > > *type=SYSCALL msg=audit(1506025995.825:46633170): arch=c000003e syscall=2 > success=yes exit=3 a0=5598f609a210 a1=200c1 a2=81a0 a3=0 items=2 ppid=21957 > pid=22355 auid=1006 uid=0 gid=0 euid=0 suid=0 fsuid=0 egid=0 sgid=0 fsgid=0 > tty=pts0 ses=361 comm="vi" exe="/usr/bin/vim.basic" key="root_action"* Typically, its expected to look at events through ausearch. It groups the records into events. You can also use aureport to see summary information. > I did read a bit on auditd from below links. *Please let me know if I am > missing something or are the calls getting audited in an expected way.* > > I went through below links; *would appreciate if someone can help with any > references which are more lucid with example*s: > > https://linux-audit.com/configuring-and-auditing-linux-systems-with-audit-da > emon/ I was not aware of that site. But some of the information appears to be dated. For example, telling people to use pam_tally2 when they should be using pam_faillock. > https://access.redhat.com/documentation/en-US/Red_Hat_Enterprise_Linux/6/ht > ml/Security_Guide/chap-system_auditing.html > > Furthermore, I would like to read much on audisp-remote to send all these > logs to a central server. I do not find any documentation on that. I see > discussion on net where people are using rsyslog instead for that. Please > help with references/links if any. Admittedly there is not much written. It is on my list of topics to blog about. But I haven't had time for blogging lately. -Steve