changed uppercase names to lowercase in definition file and added kali for attacker

big_broker.yml

 ---
 name: big-broker
 hosts:
-  - name: Web
+  - name: web
     base_box: generic/debian10
     memory: 2048
 
-  - name: Workstation
+  - name: workstation
     base_box: generic/debian10
     memory: 2048
 
-  - name: Database
+  - name: database
     base_box: generic/debian10
     memory: 2048
 
-  - name: Attacker
-    base_box: generic/debian10
+  - name: attacker
+    base_box: kalilinux/rolling-light
     memory: 2048
 
-  - name: Client
+  - name: client
     base_box: generic/debian10
     memory: 2048
 
 routers:
-  - name: Big-Broker-router
+  - name: big-broker-router
 
-  - name: Internet-router
+  - name: internet-router
 
 networks:
-  - name: Big-Broker
+  - name: big-broker
     cidr: 172.18.1.0/24
 
-  - name: Internet
+  - name: internet
     cidr: 10.1.0.0/16
 
 net_mappings:
-  - host: Web
-    network: Big-Broker
+  - host: web
+    network: big-broker
     ip: 172.18.1.5
 
-  - host: Workstation
-    network: Big-Broker
+  - host: workstation
+    network: big-broker
     ip: 172.18.1.132
 
-  - host: Database
-    network: Big-Broker
+  - host: database
+    network: big-broker
     ip: 172.18.1.14
 
-  - host: Attacker
-    network: Internet
+  - host: attacker
+    network: internet
     ip: 10.1.135.83
 
-  - host: Client
-    network: Internet
+  - host: client
+    network: internet
     ip: 10.1.17.4
 
 router_mappings:
-  - router: Big-Broker-router
-    network: Big-Broker
+  - router: big-broker-router
+    network: big-broker
     ip: 172.18.1.1
 
-  - router: Internet-router
-    network: Internet
+  - router: internet-router
+    network: internet
     ip: 10.1.0.1
 ...