security onion not receiving SPAN traffic but wireshark does

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Prashant Shrivastva

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Jan 24, 2019, 6:32:15 AM1/24/19
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Dear Experts,


I have a Security Onion Master and Security Onion Sensor (where SPAN is going in).

On the Sensor, I run "tcpdump" command and no SPAN traffic is being received on the sniffing interface configured during setup.
Also there are no external traffic (SPAN traffic) in the Bro logs, conn.log

However when I unplug the SPAN cable and put in my laptop having wireshark, I RECEIVE the SPAN TRAFFIC. Which clearly indicates that the Mirroring Port configurations are correct.

What might be blocking the IDS to receive the SPAN traffic?

FYI - I am using Surricata rules.

Also I am attaching "sostat-redacted" output with this post.

Would be great if someone could help, have been breaking my head without any progress. Thanks

Regards
Prashant
sostat-redacted.txt

Wes Lambert

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Jan 24, 2019, 7:07:38 AM1/24/19
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I'm not sure I understand.

Based on your sostat output (PF_RING stats, etc) and the interface statistics, it looks like you are receiving traffic as intended.

Could you be using VLAN tags or some type of encapsulation?

How are you attending to run tcpdump against the interface?

Thanks,
Wes




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Prashant Shrivastva

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Jan 24, 2019, 4:59:00 PM1/24/19
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Hi Wes,


I am running tcpdump command as below:

# tcpdump -i ens160

ens160 is SPAN interface. I also ran tcpdump -i ens192 , and ens192 is management interface.

I only receive Broadcast and internal securityonion traffic in the tcpdump commands.

However when i plug off the SPAN cable from server (Esxi) and plung my laptop, then wireshark shows all the traffic including external and inbound.

Also there is no traffic apart from Broadcast and internal security onion traffic in my Bro logs and neither any thing gets fired in sguil database.


Thanks
Prashant
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Brian Dorr

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Jan 24, 2019, 5:13:19 PM1/24/19
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Can I ask what type of hardware is your sensor on? Standalone? Are you using virtual at all?

Prashant Shrivastva

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Jan 25, 2019, 11:27:22 AM1/25/19
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Hi , 

It’s a Dell hardware , installed with ESXi and a virtual server is hosting my Security onion sensor . 
Now, I have configured a virtual switch which maps the physical adapter with the virual interface .
They are mapped to two virtual interface which is shown in the sensor VM . 
The sensor was working perfectly fine , but i had to reinstall the sensor as there was a data center activity. 

Thanks 
Prashant 
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Thanks
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Prashant Shrivastva
8050674842

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Brian Dorr

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Jan 25, 2019, 1:28:06 PM1/25/19
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I would double check the ports you have set up ass pass through, based off everything you said, this seems to be where the issue exists. 

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Thanks
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Prashant Shrivastva
8050674842

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Thanks
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Prashant Shrivastva
8050674842

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ledin...@gmail.com

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Jan 26, 2019, 4:20:50 AM1/26/19
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Hi Prashant,

Be sure to check the MAC address setting for the SPAN interface. There are some key ESXi settings that will prevent traffic from flowing as expected. I will dig into my notes tomorrow morning to provide more details if you haven’t got this resolved by then.

Prashant Shrivastva

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Jan 26, 2019, 11:08:51 AM1/26/19
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Hi Ledingtech,


Please let me know more details about this. I am really not sure what MAC address settings for SPAN need to be checked. Thanks

Regards
Prashant

On Sat, Jan 26, 2019 at 1:20 PM <ledin...@gmail.com> wrote:
Hi Prashant,

Be sure to check the MAC address setting for the SPAN interface.  There are some key ESXi settings that will prevent traffic from flowing as expected.  I will dig into my notes tomorrow morning to provide more details if you haven’t got this resolved by then.

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ledin...@gmail.com

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Jan 26, 2019, 11:44:27 AM1/26/19
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Good morning Prashant,

The key thing is to ensure promiscuous mode is enabled. I believe there was also one other setting that I had to modify but it escapes me at present but I will keep digging...

https://docs.vmware.com/en/VMware-vSphere/6.7/com.vmware.vsphere.security.doc/GUID-92F3AB1F-B4C5-4F25-A010-8820D7250350.html

ledin...@gmail.com

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Jan 26, 2019, 7:02:05 PM1/26/19
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Hi Prashant,

I checked my notes and the other feature I was thinking of is "Allow forged transmits" but this would not be relevant for a SPAN port capturing traffic.

So I think the promiscuous mode setting might be part of the issue...

Prashant Shrivastva

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Jan 27, 2019, 12:20:35 AM1/27/19
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Thank you for reply . But promiscuous mode enable was the first thing I checked . 
Promiscuous mode is enabled on the virtual adapter as well as on the virtual switch . 

Can you let me know how to identify which is SPAN port from the Security onion vm ? 
Also I am thinking to rebuild the virtual switch configuration at ESXi level . Can you give me a guide to build vswitch please ? 

Regards 
Prashant 
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Prashant Shrivastva

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Jan 27, 2019, 1:23:00 AM1/27/19
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Hi,

So I checked and confirmed my SPAN port from Esxi, there was a discovered subnet on one of the virtual interfaces, while the other had not discovered any subnets.
I am choosing the right SPAN interface and giving the same during the setup of interfaces in SO.

The weird part is, both my interfaces (management and SPAN) show the same traffic when tcpdump is run. Both show broadcast and internal security onion master and sensor traffic.
Kindly give a solution, I have been reinstalling SO and getting no where with this one. Any settings on virtual environment?


Regards
Prashant

Prashant Shrivastva

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Jan 27, 2019, 2:11:22 AM1/27/19
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Also I would add one more information,
I am not able to edit the /etc/network/interfaces file.

It says the file is readonly file. I tried remounting the partition as read-write also, but still cannot edit the interfaces file.
This never happened before, I was always able to add the required routes after interface configuration. 

Does this give any indication or link to the problem at hand? Do i need to rebuild the whole security onion master and sensor VMs?

Regards
Prashant

Leding Tech

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Jan 27, 2019, 2:49:56 AM1/27/19
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Prashant,

What are the permissions for the the interfaces file when issuing the ls -l command?

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Prashant Shrivastva

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Jan 27, 2019, 4:52:43 AM1/27/19
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Yes regarding the interfaces file, permission was the issue. Got it fixed. A rookie mistake.
But the primary SPAN issue is still not fixed. Not getting the SPAN (mirror) traffic on the server.

Does security onion drops traffic even on tcpdump level? I thought tcpdump, when run against an interface has nothing to do with the underlying application.

Regards
Prashant

Leding Tech

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Jan 27, 2019, 12:24:34 PM1/27/19
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Just to make sure I understand your topology...

Your SO box is running as a VM on ESX and has a second interface that receives the traffic from the network you are monitoring...correct?

If so, I have this exact same setup - works fine...

Also, how are you feeding in the monitored traffic to this secondary interface?


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Prashant Shrivastva

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Jan 27, 2019, 12:42:13 PM1/27/19
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My topology :

security onion master - its a VM, which receives Beat traffic for DNS and AD monitoring

security onion sensor - its a VM on esxi and second  physical interface receives SPAN, (SPAN is configured fine as i receive required traffic when i connect the SPAN cable with wire shark laptop) this sensor is made as forwarder

Now the scenario is that the master was untouched and sensor was reinstalled, giving one virtual interface as SPAN interface and the other for management

When doing tcpdump, the traffic of SPAN is not shown, and neither anything populates on the sguil db. 
From esxi perspective the vswitch was configured to map physical nic of the server with the virtual adapters of the VM. the vswitch config was working fine.

Thanks
Prashant

Leding Tech

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Jan 27, 2019, 1:09:43 PM1/27/19
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Ok so this was working fine up until the sensor was reinstalled?


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Prashant Shrivastva

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Jan 27, 2019, 9:58:46 PM1/27/19
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Yes. Until sensor was reinstalled it was working fine . 
The reason I had to reinstall was because the span cable was pulled out of sensor in a dc activity . But now it's pushed back in . 

What do you suggest ? 

Regards 
Prashant 
Prashant,

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Thanks
with regards,
Prashant Shrivastva
8050674842



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Thanks
with regards,
Prashant Shrivastva
8050674842


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Thanks
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Prashant Shrivastva
8050674842

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Prashant Shrivastva
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Prashant Shrivastva
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Keith Roberson

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Jan 27, 2019, 10:25:57 PM1/27/19
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I was having sort of the same issue on a rebuild. I ended up deleting my known_hosts from the sensor before a rebuild (sudo -I, the cd into .ssh and rm the known_hosts file). I noticed that if I didn’t do that I would still get a complete setup and I also was able to receive traffic on my forward node using wire shark off the sniffing interface, but nothing was populating on the master node. Good luck. 

Keith Roberson
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ledin...@gmail.com

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Jan 27, 2019, 10:27:43 PM1/27/19
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Interesting - do the sensors communicate with the master via SSH?

ledin...@gmail.com

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Jan 27, 2019, 10:30:40 PM1/27/19
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Nevermind - just found the answer in the architecture diagram...good call Keith - I bet that is part of or the actual root cause here...

Keith Roberson

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Jan 27, 2019, 10:49:46 PM1/27/19
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Great. I hope it helped.

Keith Roberson
678-410-8830

> On Jan 27, 2019, at 22:30, ledin...@gmail.com wrote:
>
> Nevermind - just found the answer in the architecture diagram...good call Keith - I bet that is part of or the actual root cause here...
>

Prashant Shrivastva

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Jan 28, 2019, 6:26:13 AM1/28/19
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Hi Keith,


So you mean deleting the known_hosts file  on the sensor, and then run a setup on the sensor?
I did that, but not receiving the SPAN traffic on the interface still.

Now I am making the sensor a standalone security onion server. just to isolate if there are any misconfigs at the master and sensor relation.
So basically i am making the sensor a new standalone deployment, that is input with SPAN. I am doing this to check if everything works fine. This will tell  me if master and sensor relation is at fault or not.
If the standalone works fine, I might need to reinstall master and sensor topology. But if the same issue happens, I am getting my ESXi virtual switch config getting checked.
Shall update you. Thanks.


Regards
Prashant

Prashant Shrivastva

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Jan 28, 2019, 8:31:21 PM1/28/19
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Hi,

I reinstalled the sensor VM on esxi, and turns out that the issue of not receiving SPAN traffic still exists. So this might not be a master and sensor sync issue.
I need to review on the ESXi, again. How can i check if the ESXi is receiving SPAN?
I can log into esxi using ssh, can you tell how can I check if the SPAN traffic is hitting esxi? tcpdump doesn't work here.

Thanks
Prashant

Brian Dorr

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Jan 28, 2019, 10:57:44 PM1/28/19
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So when you added the nic, did you add it as a pci device? Your NIC should be listed if you set up pass through correctly 
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