Lecture/8

Lecture8/README.md

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+##  Network Technologies
+1. Find host of VM with ifconfig
+2. Set Vm as a server ncat -l -p 4433
+3. Test connection from mac to VM with sending file ncat <VM IP> 4433 < tcp_test![MacSend.png](images/MacSend.png)![VmFile.png](images/VmFile.png)
+4. Test TCP connection with ncat -l -p 4433 on VM and ncat <VM IP> 4433 on Mac ![testTCPconnection.png](images/testTCPconnection.png)
+5. Test UDP connection with ncat -u -l -p 4433 on VM and ncat -u <VM IP> 4433 on Mac ![testUDPconnection.png](images/testUDPconnection.png)
+6. Use -v flag to see more info about TCP connection to the listener  and random port![TCPncatvflag.png](images/TCPncatvflag.png)
+7. Use -v flag to see more info about UDP connection to the listener  and random port![UDPncatvflag.png](images/UDPncatvflag.png)
+8. We can see that TCP connection through ncat show an error when we try to connect to a closed port, while UDP connection does not show any error when connecting to a closed port. Message send from client but didn't show on server side
+9. Enable firewall on VM, request from client machine failed with timeout ![TCPwithEnableFireWall.png](images/TCPwithEnableFireWall.png)
+
+##  DHCP server 
+1. Set up DHCP server on VM using dnsmasq
+2. Configure dnsmasq by adding  /etc/dnsmasq.d new config file to set test-dnsmasq1.conf the vm listen-address and ports
+3. Validate dnsmasq config with sudo dnsmasq --test
+4. Restart dnsmasq service with sudo systemctl restart dnsmasq
+5. Check dnsmasq service status with sudo systemctl status dnsmasq --no-pager
+6. Firewall inactive on VM
+7. Check if DHCP server from my local machine with  dig -r 4433 @my.test.vm.ip vm.lab ![DHCPresponse.png](images/DHCPresponse.png)
+8. Dig google which is not in dnsmasq config 
+9. We see Answers section 6 on google and 1 on vm.lab which means that when we guery vm.lab the request is handled by dnsmasq server (address row in dnsmasq config)
+while google request forwards to upstream DNS (1.1.1.1/8.8.8.8), because it's not in dnsmasq config file. Then this aswer is cached by dnsmasq for future requests. And we can se that response time 25ms![CachedResponse.png](images/CachedResponse.png)
+
+## Split to subnets
+1. We need to have 10 subnets which contains  from 5 to 11 hosts
+2. To get 11 hosts we need to borrow 4 bits from host part (2^4=16 subnets)
+3. We can use subnet mask /28  (32-28=4 bits for host part)
+4. Subnet mask /28 in decimal is 16 addresses and we need 10 subnets -> 16*10=160 addresses
+5. We have reserved 10.0.1.0/24 and 10.0.0.32/26 -> 10.0.1.x - fully reserved for /24 and 10.0.0.32 - 10.0.0.95 reserved for /26
+6. So we can use list of subnets from:
+   10.0.0.96/28 — subnet: 10.0.0.97–10.0.0.110 - host, broadcast: 10.0.0.111
+   10.0.0.112/28 — subnet: 10.0.0.113–10.0.0.126 - host, broadcast: 10.0.0.127
+   10.0.0.128/28 — subnet: 10.0.0.129–10.0.0.142 - host, broadcast: 10.0.0.143
+   10.0.0.144/28 — subnet: 10.0.0.145–10.0.0.158 - host, broadcast: 10.0.0.159
+   10.0.0.160/28 — subnet: 10.0.0.161–10.0.0.174 - host, broadcast: 10.0.0.175
+   10.0.0.176/28 — subnet: 10.0.0.177–10.0.0.190 - host, broadcast: 10.0.0.191
+   10.0.0.192/28 — subnet: 10.0.0.193–10.0.0.206 - host, broadcast: 10.0.0.207
+   10.0.0.208/28 — subnet: 10.0.0.209–10.0.0.222 - host, broadcast: 10.0.0.223
+   10.0.0.224/28 — subnet: 10.0.0.225–10.0.0.238 - host, broadcast: 10.0.0.239
+   10.0.0.240/28 — subnet: 10.0.0.241–10.0.0.254 - host, broadcast: 10.0.0.255
+
+