Excluding audit for BIND daemon

[Rituraj Buddhisagar]

Hi,

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) .

After the exclusion - I no more see the syscall=49 line in
/var/log/audit/audit.rules. So thats a success or 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.

*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"*

root at 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

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"*

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-daemon/
https://access.redhat.com/documentation/en-US/Red_Hat_Enterprise_Linux/6/html/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.

Thanks!


Best Regards,
Rituraj B

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