RHCSA Rapid Track
List installed service units and identify which services are currently enabled and active on a server.
Outcomes
List the installed service units.
Identify active and enabled services on the system.
As the student user on the workstation machine, use the lab command to prepare your system for this exercise.
This command prepares your environment and ensures that all required resources are available.
[student@workstation ~]$ lab start services-identify
Instructions
Use the
sshcommand to log in to theserveramachine as thestudentuser.[student@workstation ~]$
ssh student@servera[student@servera ~]$List all the installed service units on the
serveramachine.[student@servera ~]$
systemctl list-units --type=serviceUNIT LOAD ACTIVE SUB DESCRIPTION atd.service loaded active running Deferred execution scheduler auditd.service loaded active running Security Auditing Service chronyd.service loaded active running NTP client/server crond.service loaded active running Command Scheduler dbus-broker.service loaded active running D-Bus System Message Bus ...output omitted...Press q to exit the command.
List all socket units, active and inactive, on the
serveramachine.[student@servera ~]$
systemctl list-units --type=socket --allUNIT LOAD ACTIVE SUB DESCRIPTION dbus.socket loaded active running D-Bus System Message Bus Socket dm-event.socket loaded active listening Device-mapper event daemon FIFOs lvm2-lvmpolld.socket loaded active listening LVM2 poll daemon socket ...output omitted... LOAD = Reflects whether the unit definition was properly loaded. ACTIVE = The high-level unit activation state, i.e. generalization of SUB. SUB = The low-level unit activation state, values depend on unit type. 13 loaded units listed. To show all installed unit files use 'systemctl list-unit-files'.Explore the status of the
chronydservice. You can use this service for network time protocol synchronization (NTP).Display the status of the
chronydservice. Note the process ID of any active daemon.[student@servera ~]$
systemctl status chronyd● chronyd.service - NTP client/server Loaded: loaded (/usr/lib/systemd/system/chronyd.service; enabled; vendor preset: enabled) Active: active (running) since Mon 2022-03-14 05:38:15 EDT; 1h 16min ago Docs: man:chronyd(8) man:chrony.conf(5) Process: 728 ExecStart=/usr/sbin/chronyd $OPTIONS (code=exited, status=0/SUCCESS)Main PID: 747 (chronyd)Tasks: 1 (limit: 10800) Memory: 3.7M CPU: 37ms CGroup: /system.slice/chronyd.service └─747 /usr/sbin/chronyd -F 2 Mar 14 05:38:15 servera.lab.example.com systemd[1]: Starting NTP client/server... Mar 14 05:38:15 servera.lab.example.com chronyd[747]: chronyd version 4.1 starting (+CMDMON +NTP +REFCLOCK +RTC +PRIVDROP +SCFILTER +SIGND +ASYNCDNS +NTS +SECHASH +IPV6 +DEBUG) Mar 14 05:38:15 servera.lab.example.com chronyd[747]: commandkey directive is no longer supported Mar 14 05:38:15 servera.lab.example.com chronyd[747]: generatecommandkey directive is no longer supported Mar 14 05:38:15 servera.lab.example.com chronyd[747]: Frequency -11.870 +/- 1.025 ppm read from /var/lib/chrony/drift Mar 14 05:38:15 servera.lab.example.com chronyd[747]: Loaded seccomp filter (level 2) Mar 14 05:38:15 servera.lab.example.com systemd[1]: Started NTP client/server. Mar 14 05:38:23 servera.lab.example.com chronyd[747]: Selected source 172.25.254.254Press q to exit the command.
Confirm that the
chronyddaemon is running by using its process ID. In the preceding command, the output of the process ID that is associated with thechronydservice is 747. The process ID might differ on your system.[student@servera ~]$
ps -pPID TTY TIME CMD 747 ? 00:00:00 chronyd747
Explore the status of the
sshdservice. You can use this service for secure encrypted communication between systems.Determine whether the
sshdservice is enabled to start at system boot.[student@servera ~]$
systemctl is-enabled sshdenabledDetermine whether the
sshdservice is active without displaying all the status information.[student@servera ~]$
systemctl is-active sshdactiveDisplay the status of the
sshdservice.[student@servera ~]$
systemctl status sshd● sshd.service - OpenSSH server daemon Loaded: loaded (/usr/lib/systemd/system/sshd.service; enabled; vendor preset: enabled) Active: active (running) since Mon 2022-03-14 05:38:16 EDT; 1h 19min ago Docs: man:sshd(8) man:sshd_config(5) Main PID: 784 (sshd) Tasks: 1 (limit: 10800) Memory: 6.7M CPU: 82ms CGroup: /system.slice/sshd.service └─784 "sshd: /usr/sbin/sshd -D [listener] 0 of 10-100 startups" Mar 14 05:38:16 servera.lab.example.com systemd[1]: Starting OpenSSH server daemon... Mar 14 05:38:16 servera.lab.example.com sshd[784]: Server listening on 0.0.0.0 port 22. Mar 14 05:38:16 servera.lab.example.com sshd[784]: Server listening on :: port 22. Mar 14 05:38:16 servera.lab.example.com systemd[1]: Started OpenSSH server daemon. Mar 14 06:51:36 servera.lab.example.com sshd[1090]: Accepted publickey for student from 172.25.250.9 port 53816 ssh2: RSA SHA256:M8ikhcEDm2tQ95Z0o7ZvufqEixCFCt+wowZLNzNlBT0 Mar 14 06:51:36 servera.lab.example.com sshd[1090]: pam_unix(sshd:session): session opened for user student(uid=1000) by (uid=0)Press q to exit the command.
List the enabled or disabled states of all service units.
[student@servera ~]$
systemctl list-unit-files --type=serviceUNIT FILE STATE VENDOR PRESET arp-ethers.service disabled disabled atd.service enabled enabled auditd.service enabled enabled auth-rpcgss-module.service static - autovt@.service alias - blk-availability.service disabled disabled bluetooth.service enabled enabled chrony-wait.service disabled disabled chronyd.service enabled enabled ...output omitted...Press q to exit the command.
Return to the
workstationsystem as thestudentuser.[student@servera ~]$
exitlogout Connection to servera closed. [student@workstation]$