Linux Networking Commands

Accessing a Service (DNS and Routing)

  1. whois
  2. dig
  3. nslookup
  4. traceroute

whois

What it does:

  • Registrar
  • Site Owner
  • DNS name server
$ whois google.com

% IANA WHOIS server
% for more information on IANA, visit http://www.iana.org
% This query returned 1 object

refer:        whois.verisign-grs.com
...
Domain Name: google.com
...
Registrar: MarkMonitor, Inc.
...
Admin Organization: Google LLC
...
Name Server: ns2.google.com
Name Server: ns4.google.com
Name Server: ns3.google.com
Name Server: ns1.google.com

dig

What it does:

  • Nameservers
  • IP-address
$ dig google.com

; <<>> DiG 9.10.6 <<>> google.com
;; global options: +cmd
;; Got answer:
;; ->>HEADER<<- opcode: QUERY, status: NOERROR, id: 27365
;; flags: qr rd ra; QUERY: 1, ANSWER: 1, AUTHORITY: 0, ADDITIONAL: 1

;; OPT PSEUDOSECTION:
; EDNS: version: 0, flags:; udp: 1220
;; QUESTION SECTION:
;google.com.			IN	A

;; ANSWER SECTION:
google.com.		154	IN	A	172.217.165.14

;; Query time: 25 msec
;; SERVER: 192.168.31.1#53(192.168.31.1)
;; WHEN: Fri May 06 14:51:07 EDT 2022
;; MSG SIZE  rcvd: 55

nslookup

What it does:

  • Nameservers
  • IP-address
$ nslookup google.com

Server:		192.168.31.1
Address:	192.168.31.1#53

Non-authoritative answer:
Name:	google.com
Address: 172.217.165.14

traceroute

What it does:

  • Routing Information
$ traceroute google.com

traceroute to google.com (172.217.165.14), 64 hops max, 52 byte packets
 1  xiaoqiang (192.168.31.1)  1.887 ms  1.416 ms  2.689 ms
 2  puma7-atom.ht.home (192.168.0.1)  3.170 ms  2.821 ms  2.547 ms
 3  173.35.242.129 (173.35.242.129)  16.129 ms  16.067 ms  24.836 ms
 4  69.63.243.53 (69.63.243.53)  17.099 ms  16.733 ms  18.268 ms
 5  69.63.250.17 (69.63.250.17)  18.352 ms
    69.63.248.17 (69.63.248.17)  15.940 ms
    69.63.250.17 (69.63.250.17)  20.007 ms
 6  209.148.235.222 (209.148.235.222)  16.884 ms  19.465 ms  22.494 ms
 7  72.14.216.54 (72.14.216.54)  17.803 ms * *
 8  * 74.125.244.161 (74.125.244.161)  23.397 ms  19.573 ms
 9  108.170.250.241 (108.170.250.241)  21.286 ms
    216.239.49.188 (216.239.49.188)  19.660 ms
    216.239.41.175 (216.239.41.175)  18.622 ms
10  216.239.40.255 (216.239.40.255)  19.962 ms
    yyz12s06-in-f14.1e100.net (172.217.165.14)  22.307 ms
    216.239.41.175 (216.239.41.175)  21.008 ms

Network Probing

  1. nmap
  2. ping/ping6
  3. netcat
  4. telnet

nmap

What it does:

  • port scanning (TCP, UDP)
$ nmap -sS localhost

ping/ping6

sending icmp pings checking latency

ping

netcat

checking connections

netcat

telnet

checking connections

telnet

Traffic Capture

  1. tcpdump
  2. wireshark

tcpdump

Traffic capture Uses bpf filters

tcpdump

wireshark

Network Stack Management

ifconfig

ifconfig

route

route

arp

arp

ip

ip

Load Testing

tcpreplay

tcpreplay

wrk2

wrk2

iperf3

iperf3

nuttcp

nuttcp

Resources