> Are there overlay networks that are not software only?
In the defense and government security space there are 'hardware' overlay network devices. One common use is extending classified 'airgapped' networks over less secure networks or the internet. 'Inline Network Encryptor' is a generic term; 'Taclane' is one brand; HAIPE is I think an applicable NSA standard.
While the M1 Garand may have been one of the greatest battle implements ever devised, it was semi-automatic, not fully automatic. The article probably refers to the M1918 BAR.
In the defense and government security space there are 'hardware' overlay network devices. One common use is extending classified 'airgapped' networks over less secure networks or the internet. 'Inline Network Encryptor' is a generic term; 'Taclane' is one brand; HAIPE is I think an applicable NSA standard.