Question regarding ntpd

[Sullivan, Daniel [CRI]]

Actually this is kind of where my head was at too.  It just didn’t look like there was any meaningful data in the audit entry (i.e. actual time values).  I appreciate you taking the time to get back to me.

Also, FWIW I am completely new to auditd.

Dan

> On Sep 27, 2016, at 7:06 PM, John Jasen <jjasen at gmail.com> wrote:
> 
> Reading this, my first thought was ntpd trying to adjust time drift on
> the client.
> 
> 
> On 09/27/2016 07:16 PM, Steve Grubb wrote:
>> On Tuesday, September 27, 2016 10:05:31 PM EDT Sullivan, Daniel [CRI] wrote:
>>> type=SYSCALL msg=audit(1475012495.972:5327): arch=c000003e syscall=159
>>> success=yes exit=0 a0=7ffd7498eb00 a1=861 a2=0 a3=1 items=0 ppid=1 pid=5357
>>> auid=4294967295 uid=38 gid=38 euid=38 suid=38 fsuid=38 egid=38 sgid=38
>>> fsgid=38 tty=(none) ses=4294967295 comm="ntpd" exe="/usr/sbin/ntpd"
>>> key="time-change”
>>> 
>>> This is generating large amounts of log data.
>> Yep.
>> 
>>> I am not an expert in auditd log analysis.  Is this expected behavior? 
>> Unfortunately for that syscall yes. Your best option is to not audit that 
>> syscall.
>> 
>> 
>>> I am unsure of what the key time-change value of this log data is, and am
>>> wondering if this indicates some sort of misconfiguration or problem with
>>> ntpd.
>> Keys are used for reporting. You can run 
>> aureport --start today --key --summary
>> to get an idea of what kinds of events you are getting. You can also use keys 
>> with ausearch to extract events that trigger on a specific rule and then feed 
>> that to aureport.
>> 
>> 
>>> From looking at the output of tcpdump it does not look like I am polling
>>> every second, so I am wondering why this activity is occurring.   If anybody
>>> could advise on how to decipher these log entries I would appreciate it. 
>>> Thank you for your help and advisement.
>> Well, using the -i option to ausearch gives more meaning:
>> 
>> type=SYSCALL msg=audit(09/27/2016 17:41:35.972:5327) : arch=x86_64 
>> syscall=adjtimex success=yes exit=0 a0=0x7ffd7498eb00 a1=0x861 a2=0x0 a3=0x1 
>> items=0 ppid=1 pid=5357 auid=unset uid=ntp gid=ntp euid=ntp suid=ntp fsuid=ntp 
>> egid=ntp sgid=ntp fsgid=ntp tty=(none) ses=unset comm=ntpd exe=/usr/sbin/ntpd 
>> key=time-change
>> 
>> But the syscall uses a single data struct and we have no visibility into that 
>> so we cannot tell any more what its doing.
>> 
>> The whole point of monitoring the time settings is that someone could tamper 
>> with logs or cause something to appear like it occurred at a different time 
>> than it really did. So, the idea is to collect this info "in case". But ntpd 
>> overwhelms logs but chronyd might be marginally better. See bz
>> 
>> https://bugzilla.redhat.com/show_bug.cgi?id=918127
>> 
>> for some discussion.
>> 
>> -Steve
>> 
>> --
>> Linux-audit mailing list
>> Linux-audit at redhat.com
>> https://www.redhat.com/mailman/listinfo/linux-audit
> 
> --
> Linux-audit mailing list
> Linux-audit at redhat.com
> https://www.redhat.com/mailman/listinfo/linux-audit


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