21 May 2018

Accessing a Guest Webservice in a Hosted VM

devopsnetworkingvirtualboxcentos

A web service running on a CentOS guest VM remained unreachable from the Windows 10 host, even after SSH and port forwarding were configured correctly.

Diagnosis

Curl with verbose output showed connections initiating but no response arriving. The culprit: the guest firewall was blocking the port, not a routing issue.

Quick Fix — Disable Firewall Temporarily (CentOS iptables)

iptables -P INPUT ACCEPT
iptables -P OUTPUT ACCEPT
iptables -P FORWARD ACCEPT
iptables -F

Permanent Fix — Open the Port (CentOS firewalld)

firewall-cmd --zone=home --add-port=8000/tcp --permanent

Working Network Configurations

Three approaches all work once the firewall is sorted:

1. NAT with port forwarding (VirtualBox)

  • Guest listens on 0.0.0.0:8000
  • VirtualBox: forward host port 8888 → guest port 8000
  • Access from host via localhost:8888

2. Bridged networking with DHCP (VirtualBox)

  • Guest gets its own IP on the local network
  • Access directly via that IP on port 8000

3. Bridged networking (VMware Workstation Player)

  • Same as above — guest gets a DHCP address on the local network

The key thing in all cases: the firewall on the guest needs to allow the port, regardless of how the host-to-guest routing is set up.