DHCP CIDRs?

[chicocanada]

Hello, I have a Hitron 300Mbps service in Calgary. Can I please have a list of the various CIDRs that Shaw leases from for my service?

Thank you

[mdk]

@chicocanada -- welcome to this peer-to-peer discussion forum, where volunteers try to help.

This forum is not a direct path to Shaw Support (1-888-472-2222). Please contact them, to get an authoritative answer.

You could try accessing: www.who.is and reading the line: Your IP-address is aaa.bbb.ccc.ddd

and then using www.arin.net/whois to find the CIDR for your subnet.

[chicocanada]

I have mine, I need the other pools they lease from as I will eventually end up in one of those. Support reacts like a deer in the headlights, unfortunately.

[mdk]

@chicocanada -- please explain your "need".

If you get a list of the current CIDRs, and then more CIDRs are allocated to Shaw, your list will become stale.

At the time that you end up in one of those, can you research your new CIDR?

[chicocanada]

Yes but I would be locked out of my remote server.

[mdk]

@chicocanada -- try again to access:  http://www.who.is

to see a line like: Your IP address is 70.66.129.3

Then, on a Windows command-line prompt, enter:   nslookup 70.66.129.3

to get output like:

Name: S01061c9d7275f847.cg.shawcable.net
Address: 70.66.129.3

The "S0106" prefix never changes.

The "cg" never changes.

The "shawcable.net" never changes.

The "1c9d7275f847" is the MAC-address of your cable-modem. It changes only when you physically replace the cable-modem, i.e., almost never changes.

So, if you always connect to "S01061c9d7275f847.cg.shawcable.net", by whatever its current IP-address is, you will be able to connect to your cable-modem, which you have configured to "port-forward" to your home server.

QED

P.S. I have seen a bit (pun intended) about the "NOIP" service, for situations like yours. Run the NOIP client on your computer, to do a real-time update of a FQDN that you can use to connect.

[chicocanada]

Thanks a lot for your input, appreciated. Unfortunately my server is remote, as in remote to me (USA). I can only think of a static IP as an alternative.

Cheers

[mdk]

@chicocanada -- Unfortunately my server is remote, as in remote to me (USA).

Your physical location should not be a problem, presuming that you currently have access to your server:

1. open a web-browser window on your server
2. access www.who.is to get the public IP-address (on Shaw's network) of your cable-modem (but you already know that IP-address -- correct?)
3. on your local computer, use the nslookup command to find the FQDN (Fully Qualified Domain Name) associated with that IP-address
4. on your local computer, connect to that FQDN, rather than trying to connect by the current IP-address (which you think that Shaw might change)
5. QED

> I can only think of a static IP as an alternative.

That's back to the original problem: if Shaw changes the public IP-address of your cable-modem, the new IP-address will be within a different CIDR, whether it is a "static" IP or a "dynamic" IP.-address.

Note that the very-first time that a specific MAC-address (such as that of your cable-modem) gets an IP-address from Shaw's DHCP-servers, "renewing" the DHCP-lease will always give you the identical IP-address, as long as your computer stays online, doing the "DHCP-renew" requests. It is only when Shaw explicitly does something, e.g., moving many Shaw customers in an area (such as a suburb) into a new CIDR, as Shaw "splits" that area into two CIDRs, that the IP-address might change.

[chicocanada]

Thank you again for your input.

I am in Calgary and my server is in the USA. The firewall of my server has all incoming IPs blocked in 'iptables' with the exception of the CIDR I am currently in.

As for a static IP, Shaw would assign a static IP to my cable modem instead of a dynamic IP, would would solve my issue.

Cheers

[mdk]

@chicocanada -- Shaw would assign a static IP to my cable modem instead of a dynamic IP

Shaw's DHCP-servers seem to ALWAYS assign the same IP-address to the MAC-address of the Shaw cable-modem, until Shaw "splits" a neighbourhood's subnet into multiple subnets, but this "split" is quite rare. So, after the split, your IPTABLES would need to be updated on your USA-based server.