Re: [Trisquel-users] Ethernet working on debian but not on trisquel?

[onpon4]

You have apt-offline on both the offline system and an online system. You  
generate a key from the offline system, transfer that over to the online  
system, and then use that with apt-offline on the online system to grab the  
packages you need. Then you take those packages back to the offline system,  
and you can install them.

The Debian page goes into more detail.