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@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 examples:
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!