Re: Excluding audit for BIND daemon

Hi Steve, Thanks for the response. Suppressing the events with -F auid!=4294967295 worked. I am seeing the events like "vi" "chmod" etc are getting audited by the system - even as a root account. I am yet to understand fully though on various rule sets and also on components like audisp / audisp-remote. So reading more .. Best Regards, Rituraj B On Fri, Sep 22, 2017 at 10:17 PM, Steve Grubb <sgrubb(a)redhat.com&gt; wrote: > 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_Enterp > rise_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 >