Snort Exclusion not working

Hi Thomas,

when reviewing the IPS logs what do you see and what is shown in the daily reports? When looking at the Dashboard do you see indications of high packet counting the IPS?

Ian

Hi Ian,

there is nothing in the log except normal snort reload messages.  I have not found how to turn on debugging for IPS yet, maybe that would give an indication.

Not sure where I'd see connections on the dashboard, but the daily report is as follows:

After the next run:

That did not change which kind of implies that the host is excluded after all but its not (or only partially). O/C it could also mean that its not using data up until the moment the report is triggered but to an earlier time (midnight?), not sure about that.

Any other ideas?

Thanks,

regards,

Thomas

Your Exception is incorrect. 

Check out the Online Help:

Note – If you want to make an intrusion prevention exception for packets with the destination address of the gateway, selecting Any in the Destinations box will not succeed. You must instead select a definition that contains the gateway's IP address, for example the Internal (Address) or the external WAN address.

Note – If you use a Sophos UTM proxy, an intrusion prevention exception has to reflect this: A proxy replaces the original source address of a packet with its own address. Thus, to except intrusion prevention for proxied packets, you need to add the appropriate interface address definition of Sophos UTM to the source Networksbox.

Basically you are using ANY because it is Server to Any or Any to Server. 

Hi,

Thanks but I don't understand why this would be applicable to my situation. The box I am excepting is not the gateway, it's just a box in the network which is identified by hostname or ip.

Could you elaborate? 

Thanks

Regards Thomas

Do you use the Proxy in UTM ? 

Transparent  so I didn't think it would be applicable?

Or is it?

Hallo Thomas,

See #2 in Rulz and also the images at the bottom of the list.  MBP's thinking of that.  Since you're using the Proxy, IPS is applied before the inbound packet has the IP of your client on it.  Try also adding your client to the Transparent Mode Skiplist.

Cheers - Bob

Hi Bob,

ok, not sure I see the relationship with using the proxy.

From #2 I see that IPS is executed early in the traffic flow, so why is that dependent on the proxy?

And deriving from that, it sounds like I would need to move the traffic of the proxy (by a proxy exception I assume), but as I see manual firewall rules are also executed after IPS, so not sure what that will help.

And basically that makes me wonder how to correctly use the exception tab of IPS in conjunction with Proxy or manual FW rules ...

Sorry, not to deep into firewalls so trying to wrap my head around

Thanks,

regards,

Thomas

Edit - rereading MBP's answer

Note – If you use a Sophos UTM proxy, an intrusion prevention exception has to reflect this: A proxy replaces the original source address of a packet with its own address. Thus, to except intrusion prevention for proxied packets, you need to add the appropriate interface address definition of Sophos UTM to the source Networksbox.

Does that mean I'd need to add my (internal) GW IP to the exclusion list for this to work? That would exclude all proxied traffic from IPS then I assume?

I see manual firewall rules are also executed after IPS, so not sure what that will help.

Both the diagrams and #2.4 make it clear that IPS is done at different times.  If the Proxy has sent the request, the response comes back to the public IP of the UTM, so your Exception doesn't apply.  If the packet is immediately sent back to the client by the connection tracker, it has the client's private IP on it when considered for the Intrusion Prevention Exception.  If you want to use the Proxy, then the Exception must be for traffic coming from the IP of the speed test website.

You also can run a speed test at the command line:

cd /home
wget https://raw.githubusercontent.com/sivel/speedtest-cli/master/speedtest.py --no-check-certificate
cc set ips status 0
sleep 15s
python speedtest.py
cc set ips status 1
sleep 30s
python speedtest.py

Cheers - Bob

I see manual firewall rules are also executed after IPS, so not sure what that will help.

Both the diagrams and #2.4 make it clear that IPS is done at different times.  If the Proxy has sent the request, the response comes back to the public IP of the UTM, so your Exception doesn't apply.  If the packet is immediately sent back to the client by the connection tracker, it has the client's private IP on it when considered for the Intrusion Prevention Exception.  If you want to use the Proxy, then the Exception must be for traffic coming from the IP of the speed test website.

You also can run a speed test at the command line:

cd /home
wget https://raw.githubusercontent.com/sivel/speedtest-cli/master/speedtest.py --no-check-certificate
cc set ips status 0
sleep 15s
python speedtest.py
cc set ips status 1
sleep 30s
python speedtest.py

Cheers - Bob

Hi Bob,

ok, slowly I begin to understand ;)

So for personal documentation

IPS protects the box (or rather protected internal networks) from traffic from 'other' networks like public ones

To and from are from an outside point of view - From is a source in a public network and 'to' has to be a public IP (like a public reachable webserver in the local network)

So I can

1. run the test on the box itself ... potentially via certificate based login and ssh exec. Possible, not really an elegant solution

2. Try to identify the top5 speedtest servers in my vicinity and add them to the exclusion rule (from:). Probably a Group of DNS Hosts/Groups will do the trick

3. Add the public IP to the exclusion rule (from:) basically allowing all (-> so i could turn it off).

Any other option?

Thanks a mil,

regards,

Thomas

1. I recommend putty for ssh using RSA key access.

2. To get a list of the ten nearest speedtest servers:

cd /home
python speedtest.py --list|grep Germany|head

From here in Oklahoma City, that gives me:

12235) Schleswiger Stadtwerke GmbH (Schleswig, Germany) [7838.13 km]
 6219) EWE TEL GmbH (Oldenburg, Germany) [7850.76 km]
 4556) TNG Stadtnetz GmbH (Kiel, Germany) [7881.42 km]
 4617) ADDIX Internet Services GmbH (Kiel, Germany) [7881.42 km]
14722) ServerRISE (Dusseldorf, Germany) [7886.90 km]
 5835) KomMITT Ratingen (Ratingen, Germany) [7886.91 km]
 5146) Consultix (Bremen, Germany) [7886.96 km]
 5747) PLUTEX GmbH (Bremen, Germany) [7886.96 km]
 5733) LWLcom GmbH (Bremen, Germany) [7886.96 km]
16596) Bremen Briteline GmbH (Bremen, Germany) [7886.96 km]

Now, go to https://www.speedtestserver.com/ and search for 12235.  That tells me I need a DNS Host for speedtest.schleswiger-stadtwerke.de to add to my Exception.  To run the speedtest against that server, I would do:

cd /home
python speedtest.py --server 12235

3. Agreed, not a good idea to create an Exception for all traffic coming to your public IP - just disable Intrusion Prevention to accomplish that.

4. Make an Exception for traffic going to your speedtest client and add the Host object for your client to the Source box in Transparent Mode Skiplist.

Cheers - Bob

BRILLIANT !!!

I never would have found that ( the skiplist) - actually had to look up where to find it... I have (wrongly it seems) handled all my exceptions with (tagged) Proxy exceptions or Filter actions ...

Many many thanks for the help:)

BR Thomas