How to transfer data via GSM network?

Question

Data transfer

Hello.
Tell.
Two laptops with linux on board. Laptops are mobile, respectively, access to the network will be through GSM modems. It is occasionally necessary to transfer a file from one laptop to another. The transfer will always take place in one direction, but this is apparently an unimportant fact.
Tell me the most unpretentious way!?? non-burning channel.
Options are possible both in an unprotected way and in a protected way.
Is it possible, when transferring, using any utilities, to upload the file to a specific directory?

Answer 1

option a) white IP, without NAT - raise any FTP server, share and transfer
option b) IP behind NAT - through torrents, BTSYNC, hamachi, if you're lucky and will work