Linux or UNIX securely copy files across a network computer

I know FTP is insecure, how do I securely copy files across a network computer? My network has Windows and Linux systems and how to copy files from one machine to another using ssh?

You need to use OpenSSH client and server technology to copy between two more networked computers. You can also find free ssh client tools. The scp command copies files between hosts on a network. It uses ssh for data transfer, and uses the same authentication and provides the same security as ssh.

Copy from Linux to Linux/UNIX system

The syntax is:
scp {source} {destination}
scp file1 file2
scp file1 user@host:/path/to/destination/
To copy file called data.txt to ras.nixcraft.in Linux system using vivek username:
$ scp data.txt vivek@ras.nixcraft.in:/home/vivek
Copy more than two files:
$ scp data.txt pic.jpg vivek@ras.nixcraft.in:/home/vivek
Copy /data directory and all files inside /data i.e. recursively copy entire directories:
$ scp -r /data/ vivek@ras.nixcraft.in:/home/vivek/
To copy a file from server2 to server1 while logged into server1:
scp vivek@server2:/my/file/location/ /path/to/destination

Copy from Windows to Linux/UNIX system

You can download any one of the following free Windows SCP client

• PSCP
• WinSCP

Just install above client and follow on screen instructions to copy files.

Category	List of Unix and Linux commands
File Management	cat
Firewall	Alpine Awall • CentOS 8 • OpenSUSE • RHEL 8 • Ubuntu 16.04 • Ubuntu 18.04 • Ubuntu 20.04
Network Utilities	dig • host • ip • nmap
OpenVPN	CentOS 7 • CentOS 8 • Debian 10 • Debian 8/9 • Ubuntu 18.04 • Ubuntu 20.04
Package Manager	apk • apt
Processes Management	bg • chroot • cron • disown • fg • jobs • killall • kill • pidof • pstree • pwdx • time
Searching	grep • whereis • which
User Information	groups • id • lastcomm • last • lid/libuser-lid • logname • members • users • whoami • who • w
WireGuard VPN	Alpine • CentOS 8 • Debian 10 • Firewall • Ubuntu 20.04