Basic Network Utilities Cheatsheet on Linux / Unix

Display Information about your connection interfaces

ifconfig -a

Examine ARP table

$ arp -a
? (192.168.0.1) at d4:6e:e:87:a8:8a on en0 ifscope [ethernet]
? (192.168.0.100) at 2:f:b5:8d:a5:2f on en0 ifscope [ethernet]
? (192.168.0.101) at 78:32:1b:ac:8d:5b on en0 ifscope [ethernet]
? (192.168.0.123) at 94:53:30:46:aa:3c on en0 ifscope [ethernet]
? (192.168.0.255) at ff:ff:ff:ff:ff:ff on en0 ifscope [ethernet]
? (224.0.0.251) at 1:0:5e:0:0:fb on en0 ifscope permanent [ethernet]
broadcasthost (255.255.255.255) at ff:ff:ff:ff:ff:ff on en0 ifscope [ethernet]

Clear ARP table

$ sudo arp -a -d
192.168.0.1 (192.168.0.1) deleted
192.168.0.100 (192.168.0.100) deleted
192.168.0.101 (192.168.0.101) deleted
192.168.0.123 (192.168.0.123) deleted
192.168.0.255 (192.168.0.255) deleted
224.0.0.251 (224.0.0.251) deleted
255.255.255.255 (255.255.255.255) deleted

Traceroute

$ traceroute -m 4 fixes.co.za
traceroute to fixes.co.za (37.139.28.74), 4 hops max, 52 byte packets
1  192.168.0.1 (192.168.0.1)  1.115 ms  0.777 ms  0.722 ms
2  * * *
3  196.38.75.109 (196.38.75.109)  9.340 ms  8.033 ms  8.117 ms
4  196.38.75.110 (196.38.75.110)  7.573 ms  8.247 ms  5.953 ms

Ping (ICMP echo)

$ ping -c 4 fixes.co.za
PING fixes.co.za (37.139.28.74): 56 data bytes
64 bytes from 37.139.28.74: icmp_seq=0 ttl=50 time=226.616 ms
64 bytes from 37.139.28.74: icmp_seq=1 ttl=50 time=245.647 ms
64 bytes from 37.139.28.74: icmp_seq=2 ttl=50 time=264.032 ms
64 bytes from 37.139.28.74: icmp_seq=3 ttl=50 time=284.747 ms

--- fixes.co.za ping statistics ---
4 packets transmitted, 4 packets received, 0.0% packet loss
round-trip min/avg/max/stddev = 226.616/255.261/284.747/21.560 ms