🚧PRÁCTICA - Comandos de red en Linux

A continuación vamos a describir un conjunto de herramientas de comandos de Linux que nos pueden ayudar a configurar y resolver incidencias en redes

IfConfig e IP

Displays network interface configuration. For example,

ifconfig eth0 

Muestra los detalles de configuración de las interfaces de Ethernet

ifup/ifdown: Activates or deactivates a network interface.

E.g., ifdown eth0

disables the Ethernet interface.

ip: Versatile command to manage network interfaces, addresses, and routes.

For instance, ip addr show

displays IP addresses assigned to all interfaces.

ping: Checks connectivity to a host by sending ICMP echo requests. E.g., ping http://google.com verifies if you can reach Google's servers.

traceroute: Determines the path packets take to reach a destination. Example: traceroute http://google.com shows the network hops to Google.

Netstat y SS

netstat: Shows network connections, open ports, and routing table.

netstat -tuln

displays listening TCP/UDP ports.

ss: Similar to netstat, provides socket-level details.

For eg. ss -tunap

to view all TCP and UDP sockets with associated processes.

Route

route: Manages IP routing table.

Example: route -n

shows the routing table with network destinations and gateways.

iptables: Powerful firewall tool.

E.g., iptables -A INPUT -p tcp --dport 22 -j ACCEPT

allows SSH traffic

NSlookup

nslookup: Queries DNS servers.

nslookup http://google.com

retrieves the IP address of Google's domain.

ARP

Manages ARP cache.

arp -a

displays the ARP table with MAC and IP address mappings.

Port display

Puertos populares en Linux:

• HTTP – TCP 80

• HTTPS – TCP 443

• POP3 – TCP 110

• SMTP – TCP 25

• SSH – TCP 22

• DNS/DOMAIN – TCP/UDP 53

Use the cat/more/less/bat or grep/egrep command to query port numbers as follows using the /etc/services file: vivek@nixcraft:$ cat /etc/services vivek@nixcraft:$ grep -w 80 /etc/services vivek@nixcraft:$ grep -E -w '53/(tcp|udp)' /etc/services

Más info: https://www.cyberciti.biz/faq/how-do-i-check-if-a-port-is-in-use-on-linux/

IWconfig

iwconfig: Configures wireless network interfaces.

Example: iwconfig wlan0 essid "MyNetwork"

sets the wireless network.

Netcat

netcat (nc): Versatile networking utility.

nc -vz google.com 80

checks if port 80 on Google is reachable.