18 - Hostname

Imagine there's 30 McDonald’s franchises operates under the same menu, layout, the branding.
- Similar to 30 Linux server which using clone OS software to duplicate.
To identify each franchises, the name pattern should follow like "MCD_Street_A", "MCD_Street_B"...
- 30 Linux hostname should be like "Host_A", "Host B"

Change hostname

Verify current hostname
- hostname
Change hostname
- hostnamectl modifies /etc/hostname automatically so it survives a reboot.
- hostnamectl hostname [New hostname]
- Example: hostnamectl hostname server1.example.com
Verify current hostname
- hostname

Set alias

Check current IP address
- ip a
- Refer IP address beside lo: (exp: eth0, ens33 or enp0s3)
Open file /etc/hosts
- sudo vim /etc/hosts --> Esc --> I --> Enter
Add new line
- [IP address] [Hostname] [Alias]
- Example: 192.168.0.110 server1.example.com server1
Save and exit:
- Esc -->:wq --> Enter
Verify alias
- ping [Alias]
- Example: ping server1

Solution

student@localhost:~$ hostname

localhost.localdomain

student@localhost:~$ hostnamectl hostname server1.example.com

student@localhost:~$ hostname

server1.example.com

student@localhost:~$ ip a

1: lo: <LOOPBACK,UP,LOWER_UP> mtu 65536 qdisc noqueue state UNKNOWN group default qlen 1000

link/loopback 00:00:00:00:00:00 brd 00:00:00:00:00:00

inet 127.0.0.1/8 scope host lo

valid_lft forever preferred_lft forever

inet6 ::1/128 scope host noprefixroute

valid_lft forever preferred_lft forever

2: enp0s3: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc fq_codel state UP group default qlen 1000

link/ether 08:00:27:51:d6:54 brd ff:ff:ff:ff:ff:ff

altname enx08002751d654

inet 192.168.0.110/24 brd 192.168.0.255 scope global noprefixroute enp0s3

valid_lft forever preferred_lft forever

inet6 2001:d08:2230:e7a1:a00:27ff:fe51:d654/64 scope global dynamic noprefixroute

valid_lft 3125sec preferred_lft 3125sec

inet6 fe80::a00:27ff:fe51:d654/64 scope link noprefixroute

valid_lft forever preferred_lft forever

student@localhost:~$ sudo vim /etc/hosts

[sudo] password for student:

student@localhost:~$ ping server1

PING server1.example/com (192.168.0.110) 56(84) bytes of data.

64 bytes from server1.example/com (192.168.0.110): icmp_seq=1 ttl=64 time=0.156 ms

64 bytes from server1.example/com (192.168.0.110): icmp_seq=2 ttl=64 time=0.039 ms

64 bytes from server1.example/com (192.168.0.110): icmp_seq=3 ttl=64 time=0.685 ms

64 bytes from server1.example/com (192.168.0.110): icmp_seq=4 ttl=64 time=0.035 ms

64 bytes from server1.example/com (192.168.0.110): icmp_seq=5 ttl=64 time=0.083 ms

--- server1.example/com ping statistics ---

5 packets transmitted, 5 received, 0% packet loss, time 4103ms

rtt min/avg/max/mdev = 0.035/0.199/0.685/0.246 ms

student@localhost:~$

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