Danke für deine Antwort. Mir steht eine VM zu Ausbildungszwecken zur Verfügung. Wenn ich einen wirklichen minimalen Server aufsetze, dann ist dieser auch über das Internet erreichbar. Mit den Modulen aus der Anleitung wird aber irgendwas blockiert?
root@server:~# iptables -L
Chain INPUT (policy DROP)
target prot opt source destination
DROP tcp -- anywhere loopback/8
ACCEPT all -- anywhere anywhere state RELATED,ESTABLISHED
ACCEPT all -- anywhere anywhere
DROP all -- base-address.mcast.net/4 anywhere
PUB_IN all -- anywhere anywhere
PUB_IN all -- anywhere anywhere
PUB_IN all -- anywhere anywhere
PUB_IN all -- anywhere anywhere
PUB_IN all -- anywhere anywhere
DROP all -- anywhere anywhere
Chain FORWARD (policy DROP)
target prot opt source destination
ACCEPT all -- anywhere anywhere state RELATED,ESTABLISHED
DROP all -- anywhere anywhere
Chain OUTPUT (policy ACCEPT)
target prot opt source destination
PUB_OUT all -- anywhere anywhere
PUB_OUT all -- anywhere anywhere
PUB_OUT all -- anywhere anywhere
PUB_OUT all -- anywhere anywhere
PUB_OUT all -- anywhere anywhere
Chain INT_IN (0 references)
target prot opt source destination
ACCEPT icmp -- anywhere anywhere
DROP all -- anywhere anywhere
Chain INT_OUT (0 references)
target prot opt source destination
ACCEPT icmp -- anywhere anywhere
ACCEPT all -- anywhere anywhere
Chain PAROLE (15 references)
target prot opt source destination
ACCEPT all -- anywhere anywhere
Chain PUB_IN (5 references)
target prot opt source destination
ACCEPT icmp -- anywhere anywhere icmp destination-unreachable
ACCEPT icmp -- anywhere anywhere icmp echo-reply
ACCEPT icmp -- anywhere anywhere icmp time-exceeded
ACCEPT icmp -- anywhere anywhere icmp echo-request
PAROLE tcp -- anywhere anywhere tcp dpt:ftp-data
PAROLE tcp -- anywhere anywhere tcp dpt:ftp
PAROLE tcp -- anywhere anywhere tcp dpt:ssh
PAROLE tcp -- anywhere anywhere tcp dpt:smtp
PAROLE tcp -- anywhere anywhere tcp dpt:domain
PAROLE tcp -- anywhere anywhere tcp dpt:www
PAROLE tcp -- anywhere anywhere tcp dpt
op3
PAROLE tcp -- anywhere anywhere tcp dpt:imap2
PAROLE tcp -- anywhere anywhere tcp dpt:https
PAROLE tcp -- anywhere anywhere tcp dpt:imaps
PAROLE tcp -- anywhere anywhere tcp dpt
op3s
PAROLE tcp -- anywhere anywhere tcp dpt:mysql
PAROLE tcp -- anywhere anywhere tcp dpt:http-alt
PAROLE tcp -- anywhere anywhere tcp dpt:tproxy
PAROLE tcp -- anywhere anywhere tcp dpt:webmin
ACCEPT udp -- anywhere anywhere udp dpt:domain
ACCEPT udp -- anywhere anywhere udp dpt:mysql
DROP icmp -- anywhere anywhere
DROP all -- anywhere anywhere
Chain PUB_OUT (5 references)
target prot opt source destination
ACCEPT all -- anywhere anywhere
Chain fail2ban-courierimap (0 references)
target prot opt source destination
RETURN all -- anywhere anywhere
Chain fail2ban-courierimaps (0 references)
target prot opt source destination
RETURN all -- anywhere anywhere
Chain fail2ban-courierpop3 (0 references)
target prot opt source destination
RETURN all -- anywhere anywhere
Chain fail2ban-courierpop3s (0 references)
target prot opt source destination
RETURN all -- anywhere anywhere
Chain fail2ban-pureftpd (0 references)
target prot opt source destination
RETURN all -- anywhere anywhere
Chain fail2ban-sasl (0 references)
target prot opt source destination
RETURN all -- anywhere anywhere
Chain fail2ban-ssh (0 references)
target prot opt source destination
RETURN all -- anywhere anywhere