Risposte:
Da man sshd
:
/etc/hosts.allow
/etc/hosts.deny
Access controls that should be enforced by tcp-wrappers are defined here.
Further details are described in hosts_access(5).
https://debian-administration.org/article/87/Keeping_SSH_access_secure offre questi esempi:
# /etc/hosts.allow
sshd: 1.2.3.0/255.255.255.0
sshd: 192.168.0.0/255.255.255.0
# /etc/hosts.deny
sshd: ALL
Il programma wrapper TCP in Mac OS X è: tcpd
Se sei dietro un router e non hai mappato la porta sul tuo computer, ciò disabilita in modo efficace l'accesso SSH da Internet.