Snort mailing list archives
Re: Snort inline latency
From: Ian Bowers <iggdawg () gmail com>
Date: Mon, 7 May 2012 10:48:15 -0400
Apologies if I misunderstood your purpose. The setup I suggested was only to calculate the difference in latency for when snort is placed inline vs snort removed from the path. This would be useful for determining if your inline snort setup is in fact a source of latency. Are you trying to determine if snort itself is a hinderance, if the physical device you've placed inline is a hinderance, or if it is something else? Regards -Ian On Mon, May 7, 2012 at 10:10 AM, Abdelmonaim Mokadem < abdelmonaim.mokadem () abovesecurity com> wrote:
Hi,**** Thanks for the reply.**** I’m not sure that putting my snort into a VLAN is gonna bring me different results from what I actually have…**** Can you explain what would putting my IPS into a VLAN change ?**** As I understand it, it would only isolate the tests, but I think it won’t change the latency nor help calculate it..**** My big problem here is to understand why my latency is so high (nearly 200 milliseconds with clean traffic, even without snort inline activated results remain unsatisfactory) and to know if my way to calculate this latency is the right one.**** Regards,**** Abdelmonaim Mokadem.**** ** ** *From:* Ian Bowers [mailto:iggdawg () gmail com] *Sent:* Friday, May 04, 2012 4:19 PM *To:* Abdelmonaim Mokadem *Cc:* snort-users () lists sourceforge net *Subject:* Re: [Snort-users] Snort inline latency**** ** ** If you have a VLAN capable switch, use VLANs to place the snort sensor inline. run your tests, calculate latency. Then use VLANs to take the sensor out of line. repeat tests. Do this a couple times to make sure you have consistent results. I use this technique all the time in my lab to toss test appliances or VMs in the path of traffic without having to mess around with cables like. IE:**** ** ** Snort inline:**** Server --- VLAN 102 ---- snort --- VLAN 103 --- router --- client**** ** ** Snort removed:**** Server --- VLAN 102 --- router --- client**** VLAN 104 --- snort --- VLAN 104**** ** ** inline, both sides of snort are on different VLANs, and act as if they're on their own little switches. The switchports are access ports so the end devices don't see the VLAN tags. In the second scenario, snort sits in its own little penalty box on VLAN 104 where the two sensor ports don't talk to anyone. the router and the server are both on VLAN 102 at this point and can communicate directly. I'm assuming a router is involved but it doesn't have to be. just eliminate the router and put the client in its place, works the same. I pick random VLANs in the 100s for most examples to discourage people from using native VLANs by mistake since that may break the scanario.**** ** ** ** ** Example switch config if you're using Cisco gear:**** ** ** INLINE:**** vlan 102**** name servernet_inside**** vlan 103**** name servernet_outside**** ** ** interface FastEthernet0/4**** description Server access port**** switchport access vlan 102**** switchport mode access**** !**** interface FastEthernet0/5**** description Snort HOME_NET port**** switchport access vlan 102**** switchport mode access**** !**** interface FastEthernet0/6**** description Snort EXTERNAL_NET port**** switchport access vlan 103**** switchport mode access**** !**** interface FastEthernet0/7**** description Router access port**** switchport access vlan 103**** switchport mode access**** ** ** ** ** REMOVED:**** ** ** vlan 102**** name servernet_inside**** vlan 104**** name on_deck**** ** ** interface FastEthernet0/4**** description Server access port**** switchport access vlan 102**** switchport mode access**** !**** interface FastEthernet0/5**** description Snort HOME_NET port**** switchport access vlan 104**** switchport mode access**** !**** interface FastEthernet0/6**** description Snort EXTERNAL_NET port**** switchport access vlan 104**** switchport mode access**** !**** interface FastEthernet0/7**** description Router access port**** switchport access vlan 102**** switchport mode access**** ** ** ** ** Regards,**** -Ian**** ** ** On Fri, May 4, 2012 at 3:35 PM, Abdelmonaim Mokadem < abdelmonaim.mokadem () abovesecurity com> wrote:**** Hi all,**** I am currently trying to calculate my snort inline latency.**** I have 2 hosts : one running snort inline and the other one which inject pcaps (a bridge is set to send back packets from the snort host machine to the injection one).**** I use tcpdump to sniff packets at the emission and at the reception from my injection host and (I match only ACK packets with a little program) then calculate the difference between the timestamps (emission and reception), but unfortunately my results are really bad…**** Can anyone tell me if I’m doing right? Or does anyone know what is the best way to calculate snort inline latency?**** Thanks,**** AM.**** **** **** ------------------------------------------------------------------------------ Live Security Virtual Conference Exclusive live event will cover all the ways today's security and threat landscape has changed and how IT managers can respond. Discussions will include endpoint security, mobile security and the latest in malware threats. http://www.accelacomm.com/jaw/sfrnl04242012/114/50122263/ _______________________________________________ Snort-users mailing list Snort-users () lists sourceforge net Go to this URL to change user options or unsubscribe: https://lists.sourceforge.net/lists/listinfo/snort-users Snort-users list archive: http://www.geocrawler.com/redir-sf.php3?list=snort-users Please visit http://blog.snort.org to stay current on all the latest Snort news!**** ** **
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Current thread:
- Snort inline latency Abdelmonaim Mokadem (May 04)
- Re: Snort inline latency Ian Bowers (May 04)
- Re: Snort inline latency Abdelmonaim Mokadem (May 07)
- Re: Snort inline latency Ian Bowers (May 07)
- Re: Snort inline latency Abdelmonaim Mokadem (May 07)
- Re: Snort inline latency Abdelmonaim Mokadem (May 07)
- Re: Snort inline latency Ian Bowers (May 04)