DGA0122 Public IPs

Unable to set or change the LAN address when using public IPs

• Date reported 2020-12-08
• Software Version 19.4 (19.4.0207-4381030)
• Status: With Technicolor

If you want to set the Local Network IP address via the web interface to a public IP then you will get the error 'Cannot use an address in this address range' and will be unable to change it.

It seems the web interface only allows RFC1918 addresses to be used as the 'Local IPv4 Address'

However, when A&A program the router via TR069, it is possible for it to be configured with a public subnet.

This bug only affects you if you want to change the Local IPv4 Address to a public IP yourself, via the web interface.

• Bulleted list item

Workaround

Staff can re-configure the LAN subnet via our TR-069 programming - this can be used if you change your block of IPs or if you want to change from using private IPs (192.168.1.1) to public ones

Another work around is to set up the router for dual LAN subnets - that is to have the private IPs as well as the Public Subnet. See: DGA0122 Dual LAN Subnets

Hacking

A user reports success by getting the web interface to do some of the work, and then rewriting the configuration variables. For example, setting static DHCP leases:

Using the web interface, attempt to enter all the static DHCP leases. Don't reboot after entering each one, hit Close and then add the next.

Now ssh to the router as user engineer and the admin password. Do

get InternetGatewayDevice.LANDevice.1.LANHostConfigManagement.DHCPStaticAddress.

(note the trailing .). This should show the MAC addresses in the Chaddr fields, but with empty Yiaddr fields where the IP addresses should be. Now use the set command to enter the IP addresses, e,g.

set InternetGatewayDevice.LANDevice.1.LANHostConfigManagement.DHCPStaticAddress.3.Yiaddr 81.187.xx.yy

Do the same for each static IP address required. Then reboot the router to make the changes active.

If you want to change the DHCP lease time to something different from 14400, the command is e.g.

set InternetGatewayDevice.LANDevice.1.LANHostConfigManagement.DHCPLeaseTime 3600

Again, reboot to make change active.