Red Hat System Administration I

Instructions

1. Use the ssh command to log in to the servera machine as the student user.

   [student@workstation ~]$ ssh student@servera
   [student@servera ~]$

2. List all the installed service units on the servera machine.

   [student@servera ~]$ systemctl list-units --type=service
     UNIT                   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.

3. List all socket units, active and inactive, on the servera machine.

   [student@servera ~]$ systemctl list-units --type=socket --all
   UNIT                   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'.

4. Explore the status of the chronyd service. You can use this service for network time protocol synchronization (NTP).

   1. Display the status of the chronyd service. 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 172.25.254.254

      Press q to exit the command.

   2. Confirm that the chronyd daemon is running by using its process ID. In the preceding command, the output of the process ID that is associated with the chronyd service is 747. The process ID might differ on your system.

      [student@servera ~]$ ps -p 747
        PID TTY          TIME CMD
        747 ?        00:00:00 chronyd

5. Explore the status of the sshd service. You can use this service for secure encrypted communication between systems.

   1. Determine whether the sshd service is enabled to start at system boot.

      [student@servera ~]$ systemctl is-enabled sshd
      enabled

   2. Determine whether the sshd service is active without displaying all the status information.

      [student@servera ~]$ systemctl is-active sshd
      active

   3. Display the status of the sshd service.

      [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.

6. List the enabled or disabled states of all service units.

   [student@servera ~]$ systemctl list-unit-files --type=service
   UNIT 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.

7. Return to the workstation system as the student user.

   [student@servera ~]$ exit
   logout
   Connection to servera closed.
   [student@workstation]$