freebsd-dev/etc/hosts.allow

#
# hosts.allow access control file for "tcp wrapped" apps.
# $FreeBSD$
#
# NOTE: The hosts.deny file is not longer used.  Instead, put both 'allow'
#       and 'deny' rules in the hosts.allow file.
# see hosts_options(5) for the format of this file.
# hosts_access(5) no longer fully applies.

#	 _____                                      _          _ 
#	| ____| __  __   __ _   _ __ ___    _ __   | |   ___  | |
#	|  _|   \ \/ /  / _` | | '_ ` _ \  | '_ \  | |  / _ \ | |
#	| |___   >  <  | (_| | | | | | | | | |_) | | | |  __/ |_|
#	|_____| /_/\_\  \__,_| |_| |_| |_| | .__/  |_|  \___| (_)
#					   |_|                   
# !!! This is an example! You will need to modify it for your specific
# !!! requirements!


# Start by allowing everything (this prevents the rest of the file
# from working, so remove it when you need protection).
# The rules here work on a "First match wins" basis.
ALL : ALL : allow

# Wrapping sshd(8) is not normally a good idea, but if you
# need to do it, here's how
#sshd : .evil.cracker.example.com : deny 

# Prevent those with no reverse DNS from connecting.
ALL : PARANOID : RFC931 20 : deny

# Allow anything from localhost
ALL : localhost : allow
ALL : my.machine.example.com : allow

# Sendmail can help protect you against spammers and relay-rapers
sendmail : localhost : allow
sendmail : .nice.guy.example.com : allow
sendmail : .evil.cracker.example.com : deny
sendmail : ALL : allow

# Exim is an alternative to sendmail, available in the ports tree
exim : localhost : allow
exim : .nice.guy.example.com : allow
exim : .evil.cracker.example.com : deny
exim : ALL : allow

# Portmapper is used for all RPC services; protect your NFS!
# (IP addresses rather than hostnames *MUST* be used here)
portmap : localhost : allow
portmap : .nice.guy.example.com : allow
portmap : .evil.cracker.example.com : deny
portmap : ALL : allow

# Provide a small amount of protection for ftpd
ftpd : localhost : allow
ftpd : .nice.guy.example.com : allow
ftpd : .evil.cracker.example.com : deny
ftpd : ALL : allow

# You need to be clever with finger; do _not_ backfinger!! You can easily
# start a "finger war".
fingerd : ALL \
	: spawn (echo Finger. | \
	 /usr/bin/mail -s "tcpd\: %u@%h[%a] fingered me!" root) & \
	: deny

# The rest of the daemons are protected. Backfinger and log by email.
ALL : ALL \
	: severity auth.info : spawn (/usr/bin/finger -l @%h | \
	 /usr/bin/mail -s "tcpd\: %u@%h[%a] tried to use %d  (denied)" root) & \
	: twist /bin/echo "You are not welcome to use %d from %h."