Fast 5464 Port forwarding

[andyc93]

I have just been upgraded to full fibre and with that I was sent a new router.  My home already has  network cabling throughout, with its own WiFi access points.  

I configured my router exactly the same as my old Fast 5364, disabling the DHCP server setting its local IP address to 192.168.100.1/32 and disabling the onboard Wifi.  All was well until I needed to forward some ports to my local server.

No matter what IP addresss I put in to the internal host box it flagged up an error for 'Invalid IP address'.

Delving further in to the code, it appears there is a regex on Device/DHCPv4/Server/Pools[0]/SubnetMask however this value is empty when the DHCP server is turned off.  This setting is also used on the Device Info page as my local subnet is shown as blank.  Perhaps a more appropriate property to use would be "Device/IP/Interfaces[0]/IPv4Addresses[0]/SubnetMask"?

However, should anybody come across this fairly rare situation, the solution is to enable the dhcp server for your current address range.  Then set your port forwards and then disable the dhcp server again.

Hope this helps.

Router: Sagecom Fast 5464

Firmware: SG4K100174

[Michelle-TalkTalk]

Morning,

Thanks for your help @KeithFrench 

Michelle

[KeithFrench]

A 24 bit mask changes everything and this is something I would have picked up on straight away, but you had said you were using a 32 bit mask.

For your information, a 32 bit subnet mask or 255.255.255.255, whilst strictly speaking it is not invalid, it is impossible to use in normal circumstances. This is because as a minimum you need these four IP addresses within a subnet:-

1. Network address
2. Broadcast address
3. First host address
4. Last host address

The smallest number of host addresses being 2, gives you a 30-bit mask, as I said in my other reply. This would be used like this, the first host would be the router's IP address and the last one would be your device's IP address, no other devices would be allocated an address. The other two addresses serve special functions.

I bet that your 5364 is running hardware revision 3.00 & firmware V174 (this actually applies to the last three or so firmware releases), as there is a bug that causes this problem you are seeing.

Hopefully, the next firmware release will solve this.

[andyc93]

@KeithFrench Sorry, I don't know why I said a 32 bit subnet mask!  I did mean /24 or 255.255.255.0.

[KeithFrench]

Hi @andyc93 

Using an IP address of 192.168.100.1/32 will mean that the network, broadcast addreses are also 192.168.100.1, which is surely invalid.

I do not know how well TalkTalk routers support VLSM, I haven't tested it. Is there a reason why you have to use a 32 bit mask? If using the router in a similar way (presumably acting as an initial router with another router's WAN port connected to a LAN port, there is another problem, because this subnet mask means that the first & last IP address in this subnet would also be 192.168.100.1.

Whilst working on Cisco routers in the commercial environment, that fully support VLSM, I would never use a mask greater than 30 bits.

[Karl-TalkTalk]

Hi

We do feedback any firmware bugs to our Devices Teams for inclusion in future firmware.  Our Community is probably responsible for at least 50% of all future firmware corrections due to reports from customers such as yourself.

Regards,

Karl.

[andyc93]

Hi Karl,

Would it be possible that this firmware bug was reported to the developers so it doesn't appear in future versions?

Regards,

Andy

[Karl-TalkTalk]

Hi

thanks for posting the solution you found, I'm sure it will help any with a similar setup.

Regards,

Karl.