Master Linux Network Commands: ifconfig, ping, traceroute, and More

ifconfig

The ifconfig utility displays and configures network interface parameters in the Linux kernel. Changes made with ifconfig are temporary and disappear after a reboot unless they are written to the interface configuration files (e.g., /etc/sysconfig/network-scripts/ifcfg-eth0).

# ifconfig
eth0: flags=4163<UP,BROADCAST,RUNNING,MULTICAST>  mtu 1500
        inet 172.24.186.123  netmask 255.255.240.0  broadcast 172.24.191.255
        ether 00:16:3e:24:5d:8c  txqueuelen 1000  (Ethernet)
        RX packets 36773275  bytes 9755326821 (9.0 GiB)
        TX packets 31552596  bytes 6792314542 (6.3 GiB)
lo: flags=73<UP,LOOPBACK,RUNNING>  mtu 65536
        inet 127.0.0.1  netmask 255.0.0.0
        RX packets 36893510  bytes 27158894604 (25.2 GiB)
        TX packets 36893510  bytes 27158894604 (25.2 GiB)

To view a specific interface, run ifconfig eth0. Assign an IP address and netmask with:

# ifconfig eth0 192.168.1.110 netmask 255.255.255.0

Enable or disable the interface with ifup eth0 and ifdown eth0 respectively.

Change the MTU size (default 1500) with: # ifconfig eth0 mtu 9000 Put the interface into promiscuous mode (requires root) with:

# ifconfig eth0 promisc

ping

The ping utility sends ICMP echo‑request packets to test connectivity. By default it runs until interrupted; use -c N to stop after N packets.

# ping 127.0.0.1
# ping www.rumenz.com
# ping -c 5 www.rumenz.com

traceroute

traceroute

displays the sequence of hops a packet traverses to reach a destination, showing each hop’s IP address and round‑trip time.

# traceroute 8.8.8.8

netstat

netstat

prints various network statistics, including routing tables, interface counters, and open sockets.

# netstat -r
Kernel IP routing table
Destination     Gateway         Genmask         Flags   MSS Window  irtt Iface
default         gateway         0.0.0.0         UG      0   0        0   eth0
link-local      0.0.0.0         255.255.0.0     U       0   0        0   eth0
172.24.176.0    0.0.0.0         255.255.240.0   U       0   0        0   eth0

dig

dig

queries DNS servers and prints detailed answer sections, useful for troubleshooting DNS resolution.

# dig www.rumenz.com
; <<>> DiG 9.11.4-P2-RedHat-9.11.4-26.P2.el7_9.7 <<>> www.rumenz.com
;; global options: +cmd
;; Got answer:
;; ->>HEADER<<- opcode: QUERY, status: NOERROR, id: 11798
;; flags: qr rd ra; QUERY: 1, ANSWER: 1, AUTHORITY: 0, ADDITIONAL: 0
;; QUESTION SECTION:
;www.rumenz.com.            IN  A
;; ANSWER SECTION:
www.rumenz.com.     583 IN  A   42.194.162.109
;; Query time: 0 msec
;; SERVER: 100.100.2.136#53(100.100.2.136)
;; WHEN: Sat Nov 20 21:45:32 CST 2021
;; MSG SIZE  rcvd: 48

nslookup

nslookup

performs DNS lookups and can query specific record types with the -type (or -t) option.

# nslookup www.rumenz.com
Server:         100.100.2.136
Address:        100.100.2.136#53

Non-authoritative answer:
Name:   www.rumenz.com
Address: 42.194.162.109

# nslookup -type=CNAME www.baidu.com
www.baidu.com is an alias for www.a.shifen.com.

route

The route command displays and manipulates the kernel IP routing table.

# route
# route add -net 10.10.10.0/24 gw 192.168.0.1
# route del -net 10.10.10.0/24 gw 192.168.0.1
# route add default gw 192.168.0.1

host

host

looks up DNS records for a given name. Use -t to specify the record type (e.g., CNAME, NS, MX, SOA).

# host www.rumenz.com
www.rumenz.com has address 42.194.162.109
# host -t CNAME www.baidu.com
www.baidu.com is an alias for www.a.shifen.com.

arp

arp

displays and modifies the ARP cache, mapping IP addresses to MAC addresses.

# arp -e
Address              HWtype  HWaddress           Flags Mask            Iface
gateway              ether   ee:ff:ff:ff:ff:ff   C      eth0

ethtool

ethtool

queries and changes Ethernet device settings such as speed, duplex, and link status.

# ethtool eth0
Settings for eth0:
        Link detected: yes

iwconfig

iwconfig

configures wireless network interfaces or displays their parameters. Install it on RHEL/CentOS with yum install -y wireless-tools.

# iwconfig eth0
eth0      no wireless extensions.

hostname

hostname

shows or sets the system’s network name. To make a permanent change, edit /etc/sysconfig/network (or /etc/hostname on newer distributions) and reboot.

# hostname
rumenz.com