Date: Fri, 12 Jan 2007 23:19:38 +0100 From: VeeJay <maanjee@gmail.com> To: maanjee@gmail.com, FreeBSD-Questions <freebsd-questions@freebsd.org> Subject: What to write in a secure hosts.allow file? Please advise Message-ID: <2cd0a0da0701121419y3df54b21me2bf8bfb3a1658d@mail.gmail.com>
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This is a sample file... What to REMOVE and What to ADD or KEEP?
# cat /etc/hosts.allow
#
# hosts.allow access control file for "tcp wrapped" applications.
# $FreeBSD: src/etc/hosts.allow,v 1.19.8.1 2006/02/19 14:57:01 ume Exp $
#
# 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 with NO_INET6=yes.
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
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."
--
Thanks!
BR / vj
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