ELK + Netflow

This guide assumes you’ve got a running ELK stack, and is tailored for a docker installation based on docker-elk. See my ELK on docker guide here

Also, the Netflow source configuration specifcs are for a Ubiquity EdgeRouter – you’ll need to get the specifics for your device if different.

Ubiquity EdgeRouter Config

configure
set system flow-accounting interface eth0
set system flow-accounting netflow version 9
set system flow-accounting netflow server <ip> port 2055
set system flow-accounting netflow enable-egress
commit
save

Logstash configure

cd ~/docker-elk

Open ./logstash/pipeline/logstash.conf in your editor

input {                                                                                                                                                                                                                                                                                               
  udp {                                                                                                                                               
    port => 2055                                                                                                                                      
    codec => netflow {                                                                                                                                
      versions => [5, 9]                                                                                                                              
    }                                                                                                                                                 
    type => netflow                                                                                                                                   
  }                                                                                                                                                   
}                                                                                                                                                                                                                                                                                                   

output {                                                                                                                                              

  }                                                                                                                                                   
  if [type] == "netflow" {                                                                                                                            
      elasticsearch {                                                                                                                                 
        index => "logstash_nf-%{+YYYY.MM.dd}"                                                                                                         
        hosts => "elasticsearch:9200"                                                                                                                 
      }                                                                                                                                               
    } else {                                                                                                                                          
        elasticsearch {                                                                                                                               
                hosts => "elasticsearch:9200"                                                                                                         
        }                                                                                                                                             
    }                                                                                                                                                 
}

Open docker-compose.yml in your editor, and add the following to the logstash service to ensure the NetFlow port 2055 is routed to the logstash container

  ports:                                                                                                                            
      - "2055:2055/udp"

Restart ELK

sudo docker-compose up -d

sudo docker-compose restart

Kibana configuration

  • Browse to Kibana
  • Goto Management, Index Pattern, and create a few pattern based on
    `logstash-nf* and select netflow.last_switched

Test

If it’s working you should see the flows in the Kibana discover tab (make sure to select logstash-nf*)

Now you can go ahead an do some data mining, visualizations and dashboards

Some filter and visualization ideas

Purpose: See what outsiders (bots/worms etc) are attempting to
connection in via your WAN interface on low ports < 1024

Chart Style: Pie
Search: netflow.l4_dst_port:<1024 AND netflow.direction:0
Buckets: Split by netflow.l4_dst_port
Add Sub-Bucket: Split by netflow.ipv4_src_addr.keyword

Purpose: Look at 23/TCP Telnet based Botnet activity over time

Chart Style: Area
Search: netflow.l4_dst_port:23 AND netflow.direction:0
Y-Axis: Count
X-Axis: Date Histogram with netflow.last_switched

Purpose: Look into what a specific LAN side IoT device is connecting too

Chart Style: Pie
Search: netflow.ipv4_src_addr:<device ip> AND netflow.direction:1
Buckets: Split by netflow.l4_dst_port
Add Sub-Bucket: Split by netflow.ipv4_src_addr.keyword

What’s next?

I’ll look to enrich the NetFlow data with:

Sources

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