Linux sicherheit

allgemein

• https://vosp.netz.coop/index.php/Ssh#sshd

Live Überwachen

# htop - bessere form von top
htop
# uptime - wie lange der rechner online ist und wieviele cpu kerne seit 1m/5m/15m durchschnittlich genutzt wurden
uptime
# letzte neustarts
last reboot

Programme

• chkrootkit - Linux rootkit scanner
• Lynis - Universal security auditing tool and rootkit scanner

lynis update info
lynis audit system

• rkhunter

rkhunter --update
rkhunter -c

Quellen

• https://www.howtoforge.com/tutorial/how-to-scan-linux-for-malware-and-rootkits/
• https://www.howtoforge.com/faq/how-to-scan-linux-for-malware

fail2ban

installation / konfiguration

den server absichern gegen DoS Angriffe

apt install fail2ban
sudo cp /etc/fail2ban/jail.conf /etc/fail2ban/jail.local

• wichtig sind die einträge zu verändern, z.B.

# "bantime" is the number of seconds that a host is banned.
bantime  = 30m

# A host is banned if it has generated "maxretry" during the last "findtime"
# seconds.
findtime  = 20m

# "maxretry" is the number of failures before a host get banned.
maxretry = 2

• Befehle

systemctl restart fail2ban.service
fail2ban-client status sshd
tail -f /var/log/fail2ban.log

• https://www.thomas-krenn.com/de/wiki/SSH_Login_unter_Debian_mit_fail2ban_absichern
• https://wiki.ubuntuusers.de/fail2ban/

unban

#fail2ban-client set YOURJAILNAMEHERE unbanip IPADDRESSHERE
fail2ban-client set sshd unbanip  8.1.8.1