freebsd-src/etc/hosts.allow

#
# hosts.allow access control file for "tcp wrapped" applications.
# $FreeBSD$
#
# NOTE: The hosts.deny file is deprecated.
#       Place 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

# Protect against simple DNS spoofing attacks by checking that the
# forward and reverse records for the remote host match. If a mismatch
# occurs, access is denied, and any positive ident response within
# 20 seconds is logged. No protection is afforded against DNS poisoning,
# IP spoofing or more complicated attacks. Hosts with no reverse DNS
# pass this rule.
ALL : PARANOID : RFC931 20 : deny

# Allow anything from localhost.  Note that an IP address (not a host
# name) *MUST* be specified for rpcbind(8).
ALL : localhost 127.0.0.1 : allow
# Comment out next line if you build libwrap without IPv6 support.
ALL : [::1] : allow
#ALL : my.machine.example.com 192.0.2.35 : allow

# To use IPv6 addresses you must enclose them in []'s
#ALL : [fe80::%fxp0]/10 : allow
#ALL : [fe80::]/10 : deny
#ALL : [2001:db8:2:1:2:3:4:3fe1] : deny
#ALL : [2001:db8:2:1::]/64 : 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

# Rpcbind is used for all RPC services; protect your NFS!
# (IP addresses rather than hostnames *MUST* be used here)
#rpcbind : 192.0.2.32/255.255.255.224 : allow
#rpcbind : 192.0.2.96/255.255.255.224 : allow
rpcbind : ALL : deny

# NIS master server. Only local nets should have access
# (Since this is an RPC service, rpcbind needs to be considered)
ypserv : localhost : allow
#ypserv : .unsafe.my.net.example.com : deny
#ypserv : .my.net.example.com : allow
ypserv : ALL : deny

# 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.
ALL : ALL \
	: severity auth.info \
	: twist /bin/echo "You are not welcome to use %d from %h."