2.4 Verify network status and switch operation using basic utilities
- 2.4.a ping
The PING utility tests connectivity between two hosts by sending an ICMP Echo Request to a destination host to verify IP connectivity. Ping can also be used to isolate network hardware problems and incompatible configurations by providing indicators of the general speed or reliability of network connections.
Command options include:
- -t : Pings the specified host until stopped
- -a : Resolves addresses to hostnames
- -n : Count Number of echo requests to send
- -l : Adjusts the size of the ping packet
- -w : Adjusts the time-out (in milliseconds)
- hostname : Tests connectivity to a particular host
- 2.4.b telnet
Short for Telecommunications network, TELNET is a text based interface protocol that provides an insecure remote access to other computers. Telnet uses a command line interface and can be accessed in Windows from the Start menu by clicking <Start>, <Run>, then by typing: telnet (somesite) 23. Port number 23 is the default port used by telnet, but is usually optional and often not required.
- 2.4.c SSH
Secure Shell (SSH) is a cryptographic remote login protocol for secure data communication over an unsecured network. Designed as a replacement for telnet and rlogin, which send information in plaintext, SSH client and server programs provide strong host-to-host and user authentication as well as a number of securely encrypted methods of communication to provide confidentiality and integrity of data. SSH supports data stream compression between the client and the server.
There are two major versions of the SSH protocol in widespread use, SSH v1 and SSH v2. SSH v2 is more secure, and includes SFTP, which is similar to FTP, but is SSH v2 encrypted.