73 lines
2.5 KiB
Plaintext
73 lines
2.5 KiB
Plaintext
#!/sbin/ipf -f -
|
|
#
|
|
# SAMPLE: PERMISSIVE FILTER RULES
|
|
#
|
|
# THIS EXAMPLE IS WRITTEN FOR IP FILTER 3.3
|
|
#
|
|
# ppp0 - (external) PPP connection to ISP, address a.b.c.d/32
|
|
#
|
|
# ed0 - (internal) network interface, address w.x.y.z/32
|
|
#
|
|
# This file contains the basic rules needed to construct a firewall for the
|
|
# above situation.
|
|
#
|
|
#-------------------------------------------------------
|
|
# *Nasty* packets we don't want to allow near us at all!
|
|
# short packets which are packets fragmented too short to be real.
|
|
block in log quick all with short
|
|
#-------------------------------------------------------
|
|
# Group setup.
|
|
# ============
|
|
# By default, block and log everything. This maybe too much logging
|
|
# (especially for ed0) and needs to be further refined.
|
|
#
|
|
block in log on ppp0 all head 100
|
|
block out log on ppp0 all head 150
|
|
block in log on ed0 from w.x.y.z/24 to any head 200
|
|
block out log on ed0 all head 250
|
|
#-------------------------------------------------------
|
|
# Invalid Internet packets.
|
|
# =========================
|
|
#
|
|
# Deny reserved addresses.
|
|
#
|
|
block in log quick from 10.0.0.0/8 to any group 100
|
|
block in log quick from 192.168.0.0/16 to any group 100
|
|
block in log quick from 172.16.0.0/12 to any group 100
|
|
#
|
|
# Prevent IP spoofing.
|
|
#
|
|
block in log quick from a.b.c.d/24 to any group 100
|
|
#
|
|
#-------------------------------------------------------
|
|
# Localhost packets.
|
|
# ==================
|
|
# packets going in/out of network interfaces that aren't on the loopback
|
|
# interface should *NOT* exist.
|
|
block in log quick from 127.0.0.0/8 to any group 100
|
|
block in log quick from any to 127.0.0.0/8 group 100
|
|
block in log quick from 127.0.0.0/8 to any group 200
|
|
block in log quick from any to 127.0.0.0/8 group 200
|
|
# And of course, make sure the loopback allows packets to traverse it.
|
|
pass in quick on lo0 all
|
|
pass out quick on lo0 all
|
|
#-------------------------------------------------------
|
|
# Allow any communication between the inside network and the outside only.
|
|
#
|
|
# Allow all outgoing connections (SSH, TELNET, FTP, WWW, gopher, etc)
|
|
#
|
|
pass in log quick proto tcp all flags S/SA keep state group 200
|
|
#
|
|
# Support all UDP `connections' initiated from inside.
|
|
#
|
|
# Allow ping out
|
|
#
|
|
pass in log quick proto icmp all keep state group 200
|
|
#-------------------------------------------------------
|
|
# Log these:
|
|
# ==========
|
|
# * return RST packets for invalid SYN packets to help the other end close
|
|
block return-rst in log proto tcp from any to any flags S/SA group 100
|
|
# * return ICMP error packets for invalid UDP packets
|
|
block return-icmp(net-unr) in proto udp all group 100
|