Re: --solved-- ; well , mostly ; was: my isp has trouble with its own dhcp assignment

On 11/6/22 18:01, spellberg_robert wrote:

>    i called "tech_support"            [ open sundays ] ,

>    she probes the nic on the old gateway ,
>    for its dhcp_addr and its mac_addr .
> then , she has me swap the boxen and
>    she probes the nic on the new gateway , similarly .
> just like that , the new_gw works just_as_well_as the old_gw .

> she tells me that the problem is that i had a different mac_addr .
> "it's a security thing" , says she .
> "you need to call `tech_support' , when you change the mac_addr ."
> 
> "if i move the old_nic to the new_gw , when i swap the boxen ,
>    then i have , still , the old mac_addr ;
>    do i need to call , still ?" , he inquired , hope_fully .
> "no , because , then , the mac_addr has not changed" ,
>    she replied , re_assuringly .

>      is there some kind of security issue w/ nic mac_addresses ?


Without MAC filtering by the ISP, if someone gains physical access to 
the modem (antenna), gateway, or the network in between, they could 
disconnect the gateway, connect their device, and use your Internet 
connection.  MAC filtering will require a skilled technician to change 
the MAC address of their device to match the MAC address of the 
authorized gateway; either by moving the NIC or via software.  So, 
congratulations!  You are a skilled technician!  :-)


My UniFi Wi-Fi network has a "MAC Authorization" filter -- either "Deny 
List" or "Allow List".  The Allow List is similar to what your ISP uses. 
  A skilled technician will change their device MAC address (and they 
will also need the passphrase to connect).


Some Apple devices with Wi-Fi have a feature called "Private Addresses", 
whereby the device provides a different MAC address to each Wi-Fi 
network it connects to.  This is to prevent tracking the device as the 
user roams across Wi-Fi networks.  A skilled technician will make a 
look-up table (for tracking) and/or change their device MAC address (for 
impersonation) (and they will also need passphrases to connect):

     https://support.apple.com/en-us/HT211227


David