HardenedBSD/etc/hosts.allow
Jordan K. Hubbard b1be9320f3 The default rule in this file actually sent mail to root as its default
action when denying access to a service.  Unfortunately, this also makes
a dandy denial-of-service attack possible.  Change to just log the event
and shoot a "go away" response back down the socket.
2000-02-17 04:52:23 +00:00

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#
# hosts.allow access control file for "tcp wrapped" applications.
# $FreeBSD$
#
# NOTE: The hosts.deny file is no 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.
ALL : ALL \
: severity auth.info \
: twist /bin/echo "You are not welcome to use %d from %h."