How To – Configure Port Forwarding using Virtual Host to access devices on Internal network

Applicable to – versions 9.5.3 build 14 or above

This article describes a detailed configuration example that demonstrates how to configure Cyberoam to provide the access of internal resources.

Article covers how to

Create virtual host

Create firewall rule to allow the inbound traffic

Virtual host

Virtual host implementation is based on the Destination NAT concept of older versions of Cyberoam.

Virtual Host maps services of a public IP address to services of a host in a private network. In other words it is a mapping of public IP address to an internal IP address. This virtual host is used as the Destination address to access internal or DMZ server.

A Virtual host can be a single IP address or an IP address range or Cyberoam interface itself. Cyberoam will automatically respond to the ARP request received on the WAN zone for the external IP address of Virtual host.

Sample schema

Throughout the article we will use the network parameters displayed in the below given network diagram. Outbound traffic from LAN and DMZ is allowed while inbound traffic is restricted. The public servers - mail and web server are hosted in DMZ.

Network components

External IP address (Public)

IP address (Internal)

Web server 203.88.135.208 192.168.1.4 (Mapped)

Mail server 204.88.135.192 192.168.1.15 (Mapped)

For virtual host:

External IP: IP address through which Internet user’s access internal server.

Mapped IP: IP address bound to the internal server.

How To – Configure Port Forwarding using Virtual Host to access devices on Internal network

How To – Configure Port Forwarding using Virtual Host to access devices on Internal network

Configuration

Entire configuration is to be done from Web Admin Console unless specified.

Step 1: Create virtual host for Web server

Go to Firewall Virtual Host Create and create virtual host with the parameters as specified in sample schema

In our example, Internet users will access internal web server using public IP 203.88.135.208 which is mapped to local IP 192.168.1.4. In other words, all the inbound requests from 203.88.135.208 will be forwarded to 192.168.1.4.

How To – Configure Port Forwarding using Virtual Host to access devices on Internal network

Note

If servers are hosted on LAN, change the Physical Zone to LAN.

In case you have custom zones, change the Physical Zones accordingly.

Public IP address is the IP address through which Internet user’s access internal server/host. If public IP address is already configured as main Interface IP or alias IP, then use the option – Interface IP to select it as an external IP or else select the option IP and add the Public IP Address.

Step 2: Create virtual host for Mail server

Go to Firewall Virtual Host Create and create virtual host with the parameters as specified in sample schema

In our example, Internet users will access internal mail server using public IP 203.88.135.192

which is mapped to local IP 192.168.1.15. In other words, all the inbound requests from

203.88.135.192 will be forwarded to 192.168.1.15.

How To – Configure Port Forwarding using Virtual Host to access devices on Internal network

Step 3: Loopback firewall rule

Once the virtual host is created successfully, Cyberoam automatically creates a loopback firewall rule for the zone of the mapped IP address. Loopback firewall rule is created for the service specified in virtual host.

Loopback rules allow same zone internal users to access the internal resources using its public IP (external IP) or FQDN.

How To – Configure Port Forwarding using Virtual Host to access devices on Internal network

For our example, DMZ to DMZ firewall rule is created as virtual host (mapped IP address) belongs to DMZ interface subnet.

Check creation of loopback rule from Firewall Manage Firewall

Step 4: Add Firewall rules

Rule 1

Go to Firewall Create Rule and create firewall rule for each server with the parameters as displayed in the below given screens.

Click Create and the Firewall Rule for Webserver will be created successfully.

How To – Configure Port Forwarding using Virtual Host to access devices on Internal network

Click Create and the Firewall Rule for Mailserver will be created successfully.

Note

Change the Destination Host according to the actual server Location (Zone).

To create firewall rules to allow internal users to access resources in DMZ using its public IP (external IP) or FQDN follow the below mentioned steps:

Go to Firewall Create Rule and create firewall rule for each server with the parameters as displayed in the below given screens.

Click Create and the Firewall Rule for Webserver will be created successfully.

How To – Configure Port Forwarding using Virtual Host to access devices on Internal network

Click Create and the Firewall Rule for Mailserver will be created successfully.

Note:

DO NOT “Apply NAT” for inbound SMTP rules. This will setup the MailServer as an OPEN RELAY.

Document version – 3.0- 12/05/2011