Troubleshooting the Single-Interface (SIF) Cyber Gateways

Issue	Troubleshooting instructions
CGW VM's/machine's network down	If the network is down or an interface isn't working properly on an Ubuntu VM, you can systematically debug the issue with the following steps: 1. Check the Network Interface Status Use the `ip` command to check if the network interface is up and has an IP address: `ip addr` Look for the network interface (e.g., `eth0`, `ens33`, `enp0s3` or `wlan0`). Confirm it has a valid IP address (e.g., `192.168.x.xx, 172.16.x.x` or `10.x.x.x` for private networks). If the interface is DOWN, bring it up using: (Replace interface_name with actual name of the interface, shown in `ip addr` output) `sudo ip link set <interface_name> up` If the interface is UP, and shows `<BROADCAST,MULTICAST,UP,LOWER_UP>` in `ip addr` output but does not have any valid IP, then check network configuration and get an IP on the interface. 2. Check Network Configuration Verify netplan is used for network configuration on VM using command `which netplan` , if it doesn't show any output then netplan is not installed. You can skip below section 2.1 and continue with section 2.2. 2.1 Configure interface using netplan Verify the configuration of the interface: `cat /etc/netplan/.yaml` Ensure file contains same interface name is present which shows in `ip addr` output DHCP:true - Ensure interface has `dhcp4: true` setting. It is case of dynamic IP allocation. DHCP:false - Ensure interface has correct settings (e.g., dhcp4: false, correct IP, gateway, and DNS). It is case of static IP allocation. Execute `sudo netplan apply` 2.2 Configure interface using command line* In case, netplan is not installed, you can configure IP address on interface using `ip` command. In case your network supports DHCP, execute command `dhclient <interface_name>`, replace interface_name with the actual name of the interface which shows in `ip addr` output. Check if interface got any IP using command `ip addr`. If it doesn't show an IP then ensure that physical cable is properly connected to your network using a switch. Follow below steps to install static IP if still VM has no IP. Check subnet of your network and get a free IP address. Note down network mask and default gateway to use for configuration. Execute below command to assign static IP (replace interface_name with actual name of the interface which shows in `ip addr` output). For eg. if your network is on subnet 192.168.1.0/24 and interface name is ens33 which uses default gateway 192.168.1.1: `sudo ip addr add 192.168.1.100/24 dev ens33` `sudo ip route add default via 192.168.1.1` Ping default gateway of the network to check if it is accessible after interface is UP and configured with valid IP: `ping <default_gw_ip>` Verify Virtualization Layer If the issue persists, ensure the VM's virtual network adapter is configured properly: In VMware/Hyper-V, ensure the adapter is set to `NAT`, `Bridged`, or `Host-only` mode (depending on your needs). Restart the VM after making changes.
Not able to SSH on CGW machine/VM	Follow above steps to verify interface is UP and has valid IP address. Compare IP of your laptop/machine with CGW VM/machine, they should be in same subnet or should be accessible. Ping CGW VM's/machine's IP address from your laptop Try SSH to CGW machine's IP
Check Internet connection on CGW VM/machine	CGW needs Internet connectivity on machine for installation and also post installation it needs internet access to provide services. Check Internet connection by using below commands: Ping Test Ping the default gateway: `ping -c 4 <gateway_IP>` If this fails, the issue might be with the local network or configuration. Ping an external server (e.g., Google): If this succeeds, then check DNS resolution. `ping -c 4 8.8.8.8` DNS Test Test DNS resolution: `nslookup google.com` If it fails, check the DNS configuration in `/etc/resolv.conf`: `cat /etc/resolv.conf` Add a DNS server if needed (e.g., `nameserver 8.8.8.8`) Any Firewall inline? Check if CGW machine's/VM's traffic is going to internet via any Firewall. If yes, verify that Firewall is not blocking CGW machine's traffic.