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Diffstat (limited to 'share/ipf/firewall.3')
| -rw-r--r-- | share/ipf/firewall.3 | 99 |
1 files changed, 99 insertions, 0 deletions
diff --git a/share/ipf/firewall.3 b/share/ipf/firewall.3 new file mode 100644 index 00000000000..d2bd60a3188 --- /dev/null +++ b/share/ipf/firewall.3 @@ -0,0 +1,99 @@ +#!/sbin/ipf -f - +# +# SAMPLE: RESTRICTIVE 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 in log proto tcp all flags S/SA head 101 group 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 in log proto tcp all flags S/SA head 201 group 200 +block in log proto udp all head 202 group 200 +block out log on ed0 all head 250 +#------------------------------------------------------- +# 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 +#------------------------------------------------------- +# 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 +# +#------------------------------------------------------- +# Allow outgoing DNS requests (no named on firewall) +# +pass in quick proto udp from any to any port = 53 keep state group 202 +# +# If we were running named on the firewall and all internal hosts talked to +# it, we'd use the following: +# +#pass in quick proto udp from any to w.x.y.z/32 port = 53 keep state group 202 +#pass out quick on ppp0 proto udp from a.b.c.d/32 to any port = 53 keep state +# +# Allow outgoing FTP from any internal host to any external FTP server. +# +pass in quick proto tcp from any to any port = ftp keep state group 201 +pass in quick proto tcp from any to any port = ftp-data keep state group 201 +pass in quick proto tcp from any port = ftp-data to any port > 1023 keep state group 101 +# +# Allow NTP from any internal host to any external NTP server. +# +pass in quick proto udp from any to any port = ntp keep state group 202 +# +# Allow outgoing connections: SSH, TELNET, WWW +# +pass in quick proto tcp from any to any port = 22 keep state group 201 +pass in quick proto tcp from any to any port = telnet keep state group 201 +pass in quick proto tcp from any to any port = www keep state group 201 +# +#------------------------------------------------------- +block in log proto tcp from any to a.b.c.d/32 flags S/SA head 110 group 100 +# +# Allow incoming to the external firewall interface: mail, WWW, DNS +# +pass in log quick proto tcp from any to any port = smtp keep state group 110 +pass in log quick proto tcp from any to any port = www keep state group 110 +pass in log quick proto tcp from any to any port = 53 keep state group 110 +pass in log quick proto udp from any to any port = 53 keep state group 100 +#------------------------------------------------------- +# 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 |