View source for Networking & remote access

The following are common and useful commands and utilities in Linux for managing networking, networking related functions, and remote access. 


== General networking== 

{| class="wikitable sortable" 
!		Command	!!	Function
|-
|	/etc/network/interfaces	||	Location of network interface information
|-
|	cd ''dir''	||	Access a directory called dir_name on a remote computer.
|-
|	curl -O ''URL''	||	Download contents of a webpage
|-
|	curl ''URL''	||	Get or display file from URL
|-
|	curl ifconfig.me	||	Find one’s external IP address 
|-
|	dig	||	Query DNS servers for information on a domain
|-
|	dig -x ''IP_address''	||	Check  DNS for reverse lookup an active IP address
|-
|	dig ''domain''	||	Find DNS information and configuration on an active domain name.
|-
|	dig@''IP'' ''domain'' -t AXFR	||	DNS Zone Transfer
|-
|	echo ''"nameserver'' '' /etc/resolv.conf	||	Add DNS Server
|-
|	echo "1" '' /proc/sys/net/ipv4/ip forward	||	Enable IP Forwarding
|-
|	ethtool eth0	||	Query or control network driver and hardware settings
|-
|	export MAC=''MAC_address''	||	Change MAC Address
|-
|	get ''file''	||	Download a file from a remote computer to the local machine
|-
|	host -I hostname	||	Display the local IP address of a specified hostname with other  information.
|-
|	host -l ''domain'' ''nameserver''	||	DNS Zone Transfer
|-
|	host ''IP''	||	Domain Lookup IP
|-
|	host domain	||	Display DNS ip address for domain
|-
|	hostname -i	||	Display the network address of the host name.
|-
|	hostname -I	||	Display all local IP addresses
|-
|	hostname -I	||	Display IP address
|-
|	hostnamectl ''set-hostname hostname''	||	Manage hostname (/etc/hostname) without restarting
|-
|	ifconfig	||	Display the IP and MAC address of a system
|-
|	ifconfig -a	||	Display all network interfaces and IP addresses
|-
|	ifconfig ''interface'' ''IP/CIDR''	||	Set IP and netmask
|-
|	ifconfig ''interface'' mtu ''size''	||	Change MTU size
|-
|	ifconfig eth0	||	Display eth0 address and details
|-
|	ifconfig eth0 ''IP'' up	||	Activate eth0 with specified IP address
|-
|	ifconfig eth0 down	||	Deactivate eth0
|-
|	ifconfig eth0 up	||	Activate eth0
|-
|	ifconfig eth0:1 ''IP/CIDR''	||	Set virtual interface
|-
|	ifconfig int hw ether ''MAC_address''	||	Change MAC Address
|-
|	ifdown ''interface''	||	Down an interface
|-
|	ifup ''interface''	||	Up an interface
|-
|	ip a	||	Display all system IP addresses
|-
|	ip addr add ''IP_address'' dev eth1	||	Add a temporary IP address to interface eth1
|-
|	ip addr show	||	Display  network interfaces and their related IP addresses
|-
|	ip address add ''IP_address''	||	Used under interface eth0 to assign an IP address.
|-
| ip r || Show IP addresses for local host (same as 'route') 
|-
|	lsof -i	||	Established Connections
|-
|	mail -s 'mail_subject' -c 'cc-mail_address' -b 'bcc-mail_address' 'to-mail_address'	||	Send an email from the terminal
|-
|	nc -vz ''host'' ''port''	||	Scan port in host
|-
|	netstat -ant	||	TCP connections
|-
|	netstat -anu	||	UDP Connections
|-
|	netstat -nutlp	||	Display listening tcp and udp ports and corresponding programs (a netstat command)
|-
|	netstat -pnltu	||	Display all listening ports (a netstat command)
|-
|	netstat -r -v	||	Prints network routing, information, and connections
|-
|	netstat -tuln	||	All tcp and udp listening ports
|-
|	netstat -tulpn	||	Connections with PIDs
|-
|	ping -c ''hostname''	||	Ping an IP address and stop after a specified number of replies
|-
|	ping ''domain''/''IP''	||	Ping a host by domain name or IP (send ICMP echo request)
|-
|	ping host-ip	||	Check connectivity between two hosts
|-
|	quit	||	Logout from a remote connection.
|-
|	route, route -n	||	Display kernel IP routing table (local host IP addresses) 
|-
|	route add -net ''IP''	||	Tell other systems which network to route a system on
|-
|	route add default gw ''IP''	||	Add a default gateway
|-
|	route add default gw ''IP''	||	Set Default Gateway
|-
|	share ''user'' ''IP'' c$	||	Mount Windows Share
|-
|	smb://''IP''/''sharename''	||	Access Windows SMB Share
|-
|	ss -tuln	||	All tcp and udp listening ports
|-
|	ssh -i	||	Grants user access to openSSH client.
|-
|	SSH ''user''@''ip_address'' OR ''host''	||	Enables SSH login or sign-in to a remote Linux machine by specifying the machine's username and IP address.
|-
|	tcpdump	||	Dump network traffic
|-
|	telnet	||	Grants access to the Telnet protocol user interface.
|-
|	traceroute	||	Show places where packets travel to reach an address
|-
|	watch ss -tp	||	Network Connections
|-
|	wget --random-wait -r -p -e robots=off -U ''URL''	||	Download an entire website 
|-
|	wget -c ''file''	||	Continue an interrupted download
|-
|	wget ''URL''	||	Download file from a URL, http://domain.com/file
|-
|	whois ''domain''	||	Show whois information for a domain
|}				
				
				
				
==Networking: Remote access==

{| class="wikitable sortable" 
!		Command	!!	Function
|-
|	/etc/ssh/sshd_config ‘’OR’’ ssh_config	||	SSHD configuration file (e.g., to change login options or assigned port numbers)
|-
|	get ''file''	||	Download a file to a local computer
|-
|	put ''file''	||	Upload a file to a remote computer
|-
|	rsync -a /home /backups/	||	Synchronize /home to /backups/home
|-
|	rsync -avz /home server:/backups/	||	Synchronize files/directories between the local and remote system with compression enabled
|-
|	scp -r server:/var/www /tmp	||	Copy all files and directories recursively from server to the current system's /tmp folder.
|-
|	scp ''file" server:/tmp	||	Copy file to a remote server (e.g., into the tmp folder)
|-
|	scp ''file" server:/tmp	||	Secure copy file.txt to the /tmp folder on server
|-
|	scp ''user''@''host'':''remote'' ''local''	||	Copy file from host to local machine
|-
|	scp server:/var/www/*.html /tmp	||	Copy *.html files from server to the local /tmp folder.
|-
|	ssh -i	||	Open an SSH client; grant user access to SSH client
|-
|	ssh -p [port'' ''user''@''host''	||	Connect to a remote machine or server through a specified port.
|-
|	ssh -V	||	Display SSH version installed on the machine
|-
|	ssh ''user''@''host''	||	Connect to host as user
|-
|	ssh ''user''@''host''	||	Connect to a remote machine or server based on a valid username and hostname or IP address.
|-
|	SSH ''user''@ip_address OR ''host''	||	Enables SSH login or sign-in to a remote Linux machine by specifying the machine's username and IP address.
|-
|	ssh host	||	Connect to host as user via SSH port (default port 22)
|-
|	ssh-copy-id -i .ssh/keyfilename.pub user@hostname	||	Copy public SSH key to remote server  
|-
|	ssh-copy-id ''user''@''host''	||	Add current user’s key to host to enable keyed or passwordless login
|-
|	ssh-keygen -t ed25519 -f ~/.ssh/[filename] -C “[optional comment]”	||	Generate SSH key on client computer
|-
|	sudo nano /etc/ssh/sshd_config, PasswordAuthentication no	||	Disable SSH password login (set PasswordAuthentication to ‘no’, PermitRootLogin to ‘no’, PubkeyAuthentication to ‘yes’)
|-
|	sudo systemctl reload sshd	||	Restart SSH server 
|-
|	systemctl status sshd	||	Show status of SSH server on host machine 
|-
|	telnet ''host''	||	Uses telnet's default port 23 to connect to a target hostname, remote machine, or server.
|}				





==See also==

<categorytree mode=pages>Linux</categorytree>


[[Category:Linux]]