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BBKing · 13-06-2004, 13:54

Firstly a bit of education. Addresses starting 172.16 to 172.31, 192.168 or 10 are *private* addresses. This means companies or individuals can use them internally but they are not reachable from outside the company. NTL use the 10 and 172.16-31 ranges for addressing your cable modem, since there's no reason why the modem itself should be accessible from outside ntl.

Thus 172.16.55.254 is a private non-routable address used on the ntl network. In fact, it's the default gateway for your cable modem and just happens to be the first address on your local UBR (the device that connects you to the Internet). Thus it is used as the source for any traffic the UBR sends to your PC, including DHCP renewals.

Robin Walker in his cable modem notes recommends allowing this IP address through the firewall. There's certainly nothing to worry about.

13-06-2004, 13:54	#6
BBKing R.I.P. Join Date: Jun 2003 Location: London Services: 20Mb VM CM, Virgin TV Posts: 5,983	Re: Firewall spots continuous traffic Firstly a bit of education. Addresses starting 172.16 to 172.31, 192.168 or 10 are private addresses. This means companies or individuals can use them internally but they are not reachable from outside the company. NTL use the 10 and 172.16-31 ranges for addressing your cable modem, since there's no reason why the modem itself should be accessible from outside ntl. Thus 172.16.55.254 is a private non-routable address used on the ntl network. In fact, it's the default gateway for your cable modem and just happens to be the first address on your local UBR (the device that connects you to the Internet). Thus it is used as the source for any traffic the UBR sends to your PC, including DHCP renewals. Robin Walker in his cable modem notes recommends allowing this IP address through the firewall. There's certainly nothing to worry about.