secure ftp system IP and Protocol Diagram

SFTP im TCP/IP‑Protokollstapel:
Anwendung SFTP
Transport TCP
Internet IP (IPv4, IPv6)
Netzzugang Ethernet Token

SFTP – SSH File Transfer Protocol – usually runs over TCP port 22

FTP – plain, old file transfer protocol – usually runns over TCP port 21 (+ opens separate ports for data transfer)

FTP/SSL – FTP over TSL/SSL channel.

FTPS – same as FTP/SSL

Secure FTP – either SFTP or FTPS

More info:



FTP classic

  • Plain FTP
  • Clear-text password sent over the network
  • Typically runs over TCP port 21
  • Defined by RFC 959 and 1123
  • Implemented in FTP/SSL component



  • Often called ‘FTPS’
  • Often called ‘Secure FTP’
  • Plain FTP over TLS/SSL channel
  • Password is encrypted
  • Transfer is encrypted
  • Typically runs over TCP port 21 or 990
  • Defined by RFC 959, 1123, 4217 and 2228
  • Implemented in FTP/SSL component


SSH File Transfer Protocol

  • SSH File Transfer Protocol
  • Has nothing common with original FTP
  • Often called ‘Secure FTP’
  • Password is encrypted
  • Transfer is encrypted
  • Typically runs over TCP port 22
  • RFC not yet finished
  • Implemented in SFTP component



Linux Init Processes

The Linux Init Processes:

The init process is the last step in the boot procedure and identified by process id “1”. Init is responsible for starting system processes as defined in the /etc/inittab file. Init typically will start multiple instances of “getty” which waits for console logins which spawn one’s user shell process. Upon shutdown, init controls the sequence and processes for shutdown. The init process is never shut down. It is a user process and not a kernel system process although it does run as root.

System Processes:

Process ID Description
0 The Scheduler
1 The init process
2 kflushd
3 kupdate
4 kpiod
5 kswapd
6 mdrecoveryd

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