How to Use Shell Scripts to Retrieve IP, MAC, and Speed of Linux Network Interfaces

1) List Available Network Interfaces

Use ip combined with awk to filter interfaces whose state is UP :

[root@localhost ~]# ip ad | awk '/state UP/ {print $2}'
ens33:
ens38:

2) View IP Addresses

Show each interface’s IPv4 and IPv6 addresses:

[root@localhost ~]# ip -o addr | awk '/inet/ {print $2,$4}'
lo 127.0.0.1/8
lo ::1/128
ens33 192.168.43.138/24
ens33 fe80::214:53b4:43f6:5495/64
ens38 172.25.254.130/24
ens38 fe80::c2ff:9dbc:76be:6dd9/64

Or display only IPv4 addresses:

[root@localhost ~]# ip addr | grep inet | grep -v 'inet6' | awk '{print $NF, $2}'
lo 127.0.0.1/8
ens33 192.168.43.138/24
ens38 172.25.254.130/24

3) View MAC Addresses

Show the MAC address of a specific interface (e.g., ens33):

[root@localhost ~]# ip link show ens33 | awk '/link/ {print $2}'
00:0c:29:ee:d9

To list MAC addresses for all active interfaces, you can use a small script:

# cat mac-address.sh
#!/bin/bash
ip addr | awk '/state UP/ {print $2}' | sed 's/://' | while read iface; do
  echo "$iface:"
  ethtool -P $iface
 done

4) Check Interface Speed

Use ethtool to query the speed of a particular interface:

[root@localhost ~]# ethtool ens33 | grep "Speed:"
Speed: 1000Mb/s

To obtain speeds for all active interfaces, another script can be used:

# cat port-speed.sh
#!/bin/bash
ip addr | awk '/state UP/ {print $2}' | sed 's/://' | while read iface; do
  echo "$iface:"
  ethtool $iface | grep "Speed:"
 done

5) Comprehensive NIC Information Script

The following Bash script prints the hostname, then for each active interface displays its name, IPv4/IPv6 addresses, MAC address, and link speed:

# cat nic-info.sh
#!/bin/bash
hostname
echo "-------------"
for iface in $(ip addr | awk '/state UP/ {print $2}'); do
  echo "$iface"
  ip addr show $iface | grep inet | awk '{printf "%s:\t%s
", $1, $2}'
  ip link show $iface | grep link | awk '{printf "MAC:\t%s
", $2}'
  ethtool $iface | awk '/Speed/ {printf "%s\t%s
", $1, $2}'
done

Running the script produces a concise summary of each network interface’s IP configuration, MAC address, and negotiated speed.