Generating own DHCP Option 61 login details for Sky fibre broadband

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Generating own DHCP Option 61 login details for Sky fibre broadband

Post by embleton » Sat Aug 18, 2018 6:26 pm

In my option, there is no requirement to capture anything over ethernet from a router using Wireshark for Sky Fibre VDSL, under Dynamic Host Control Protocol (DHCP) option 61 which may be a populated for DHCP Option 61 client identifier but is not a requirement. I've also read RFC 4388 page 8, 9 and 17 6.4.2 paragraph 5 which I have found more than interesting. It does confirm that the unique identifier can be populated but it isn't a requirement, that's in page 17 stuff. It is made up of a MAC on the Ethernet Wide Area Network (WAN) port and timestamp usually when generating such for version 1 UUID's for populating the fields in DHCP option 61.

I cannot understand why router manufacturers aren't generating a UUID on the third party router when the connection and using the fields between the DHCP client and DHCP server is established and used. The fields under DHCP option 61 should really be unique on every WAN connection anyway. And the fields shouldn't really be static but Sky allows that it would seem. Without that being unique on every established connection the user equipment cannot be tracked for maintenance purposes and DHCP allocation address pool.

One only needs a unique MAC and timestamp but that is taken from the router for the UUID's and that is why it needs capturing from the LAN for it is broadcast from the WAN. But for me, I'd try using a version 4 UUID which does offer UUID's without a MAC component (it does look the same but isn't tied to the router WAN ethernet interface) and this could be used in the client exchange with the DHCP Option 61.

There are version 4 UUID generators on the internet.
UUID e11f1b12-1332-459a-80d6-77a6b2b278be

An example UUID above, which is unique. One could use the 1st section for password & the last section for a MAC without the hyphen in the UUID, but generate your own UUID using an internet generator for uniqueness. Site https://www.uuidgenerator.net will generate the UUID and use the Version 4 UUID generator.

So, the login details should be as below for the above UUID. The username is the MAC, so if this is needed don't clone it from Sky router just use this example for the MAC address for the third party router. The hostname is generated for a third-party router that uses that instead of username and password, as below.

username: 77a6b2b278be@skydsl
password: e11f1b12

hostname: 77a6b2b278be@skydsl|e11f1b12 (Asus routers merlin firmware).
hostname with quotes: ""77a6b2b278be@skydsl|e11f1b12";" (Ubiquiti routers).

https://www.rapidtables.com/convert/num ... o-hex.html
In hex without spaces: 37376136623262323738626540736b7964736c7c6531316631623132 (For DD-WRT firmware).

The @skydsl is a static component which is known on other forums for the client DHCP exchange that is followed by some sections of a correctly formatted UUID. The client ID consists of some sections of the UUID as well. The UUID sections of the fields are a static length for DHCP option 61 in MER, I think I've got the right size for each field but have not tried it. They are 12 hex long for the username and 8 hex long passwords with the @skydsl section in between.

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