Here are some basic network commands in Unix with detailed explanations and examples:
1. ping
Command:
The ping
command is used to test network connectivity between your computer and a remote host using the Internet Control Message Protocol (ICMP).
Basic Usage:
ping [options] host
host
: The hostname or IP address of the remote host to ping.
options
: Optional flags to modify the behavior of ping
.
Example:
ping www.google.com
Explanation:
This command sends ICMP echo request packets to www.google.com
to check if it's reachable and measure the round-trip time for responses.
Common Options:
-c count
: Specify the number of packets to send (default is infinite).-s size
: Set the size of the ICMP packets.-i interval
: Set the interval between sending packets.-t timeout
: Set the maximum time to wait for a response.
2. ifconfig
Command:
The ifconfig
(interface configuration) command is used to display and configure network interfaces on your system.
Basic Usage:
ifconfig [interface] [options]
interface
: The name of the network interface to configure or display.
options
: Optional flags to control the behavior of ifconfig
.
Example:
ifconfig eth0
Explanation:
This command displays network configuration information for the eth0
network interface.
Common Options:
-a
: Display all interfaces (including inactive ones).interface IP_ADDRESS
: Configure the IP address of a network interface.interface down
: Disable a network interface.interface up
: Enable a network interface.
3. netstat
Command:
The netstat
(network statistics) command is used to display network-related information, such as open network connections, routing tables, and network interface statistics.
Basic Usage:
netstat [options]
options
: Optional flags to specify what network information to display.
Example:
netstat -tuln
Explanation:
This command displays a list of all listening (bound) TCP and UDP network services and their associated port numbers.
Common Options:
-t
: Display TCP connections.-u
: Display UDP connections.-l
: Display listening sockets.-n
: Display numerical addresses instead of resolving hostnames.-r
: Display the routing table.-i
: Display network interfaces and their statistics.
4. ssh
Command:
The ssh
(Secure Shell) command is used to establish secure remote shell sessions and securely transfer files between systems over a network.
Basic Usage (Remote Shell):
ssh [user@]host [command]
user
: The username to use for the remote session (optional).
host
: The hostname or IP address of the remote server.
command
: A command to execute on the remote server (optional).
Example (Remote Shell):
ssh user@hostname
Explanation:
This command establishes a secure shell session with the remote host hostname
using the user
as the username.
Basic Usage (File Transfer):
scp [options] [source] [destination]
options
: Optional flags to modify the behavior of scp
.
source
: The source file or directory to copy from.
destination
: The destination file or directory to copy to.
Example (File Transfer):
scp myfile.txt user@hostname:/path/to/destination
Explanation:
This command securely copies myfile.txt
from the local system to the remote server hostname
in the specified destination directory.
Common Options (Remote Shell):
-p port
: Specify a custom SSH port.-i identity_file
: Use a specific SSH private key for authentication.
Common Options (File Transfer):
-r
: Recursively copy directories.-P port
: Specify a custom SCP port.
These basic network commands are essential for troubleshooting, configuring, and managing network connections and resources in Unix-like operating systems. They provide valuable insights into network status and enable secure remote communication and file transfers.