CentOS 8

chrony

# chrony tracking
Reference ID    : BC44355C (tor-relais2.link38.eu)
Stratum         : 3
Ref time (UTC)  : Fri Oct 04 10:01:42 2019
System time     : 0.000004382 seconds fast of NTP time
Last offset     : -0.004034238 seconds
RMS offset      : 0.004034238 seconds
Frequency       : 1.807 ppm fast
Residual freq   : -681.512 ppm
Skew            : 11.315 ppm
Root delay      : 0.036042333 seconds
Root dispersion : 0.034783933 seconds
Update interval : 1.8 seconds
Leap status     : Normal

# chronyc sources
210 Number of sources = 3
MS Name/IP address         Stratum Poll Reach LastRx Last sample               
===============================================================================
^+ tor-relais2.link38.eu         2   6   377    25    -23us[ +745us] +/-   21ms
^* v35005.php-friends.de         2   6   377    24   +922us[+1691us] +/-   13ms
^+ stratum2-3.NTP.TechFak.N>     2   6   377    24   -874us[ -105us] +/-   19ms

PowerTools Repository

yum install epel-release
yum config-manager --set-enabled PowerTools

cockpit

# dny -y install cockpit
# systemctl enable --now cockpit.socket
# firewall-cmd --add-service=cockpit --permanent
# firewall-cmd --reload

rename interface devices

Siehe systemd.link Manpage

Verzeichnis /etc/systemd/network anlegen

mkdir /etc/systemd/network

und dort eine Datei 10-net0.link mit folgenden Inhalt anlegen

vi /etc/systemd/network/10-net9.link

[Match]
MACAddress=00:a0:de:63:7a:e6

[Link]
Name=net0

secure sshd with fail2ban

zuerst wird fail2ban installiert

dnf install fail2ban

anschließend eine lokale Konfigurationsdatei erzeugt.

vi /etc/fail2ban/jail.local
[DEFAULT]
bantime  = 1d
findtime  = 300
maxretry = 3
banaction = iptables-multiport
backend = systemd

[sshd]
enabled = true

und danach fail2ban und sshd restartet.

systemctl restart fail2ban
systemctl restart sshd

• Statusabfrage*

fail2ban-client status
Status
|- Number of jail:	1
`- Jail list:	sshd