Date: Sat, 16 Dec 2006 16:06:50 +0100 From: "Jurjen Middendorp" <jurjenm@stack.nl> To: freebsd-security@freebsd.org Subject: ipfw: did i forget anything? Message-ID: <20061216150650.GA876@jurjenm.stack.nl>
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Hello, i hope this is the right list! I tried making a firewall for my laptop..it wasn't as terribly difficult as i thought it would be but i'm not sure if i forgot anything. And things can always be done better :) I'm not sure what i should've put under incoming connections... what i have put there now is pretty useless because the default is to deny, but should i accept any incoming connections that don't match the dynamic rules? I just want to be able to surf the internet without too much trouble and send e-mail and pretty much deny everything else. If someone would have the time to have a quick look at this to see if there's anything wrong with it i would really appreciate it! Bye, jurjen. ps. here is my ruleset: #!/bin/sh ipfw -q flush cmd="ipfw -q add" ks="keep-state" oif="ath0" #setup the loopback $cmd 001 allow all from any to any via lo0 $cmd 002 deny all from any to 127.0.0.0/8 $cmd 003 deny ip from 127.0.0.0/8 to any #check state of incoming packets $cmd 010 check-state #### # Outgoing #allow outgoing connections to internetsites, ssh sites # webservers and stack. (keep-state) #to stack (student computer organisation thing) $cmd 020 allow all from me to 131.155.0.0/16 via $oif $ks #allow ssh $cmd 021 allow all from me to any 22 $ks #internet sites: $cmd 032 allow tcp from me to any 80 $ks #https $cmd 033 allow tcp from me to any 443 $ks #gopher $cmd 034 allow tcp from me to any 70 $ks #other e-mail #pop $cmd 040 allow tcp from me to any 110 $ks #imap $cmd 041 allow tcp from me to any 143 $ks #allow dns queries $cmd 050 allow udp from me to any 53 $ks #allow ntp (?) queries $cmd 051 allow udp from me to any 123 $ks #i can send icmp myself $cmd 060 allow icmp from me to any out via $oif $ks #but others can't $cmd 061 deny icmp from any to me # #root can do anything $cmd 070 allow tcp from me to any out via $oif setup $ks uid root #log other outgoing packets $cmd 071 deny log all from any to any out via $oif #### # Incoming #deny incoming from private networks $cmd 100 deny all from 192.168.0.0/16 to any in via $oif #RFC 1918 $cmd 101 deny all from 172.16.0.0/16 to any in via $oif #RFC 1918 $cmd 102 deny all from 10.0.0.0/8 to any in via $oif $cmd 105 deny all from 169.254.0.0/16 to any in via $oif #DHCP auto $cmd 106 deny all from 192.0.2.0/24 to any in via $oif #reserved $cmd 108 deny all from 192.168.0.0/16 to any in via $oif #D & E class # multicast #block samba stuff $cmd 120 deny tcp from any to me 137 in via $oif $cmd 121 deny tcp from any to me 138 in via $oif $cmd 122 deny tcp from any to me 139 in via $oif #log ACK packets that didn't match the dynamic ruleset $cmd 130 deny log all from any to any established in via $oif #Now log some stuff in case i did something wrong $cmd 999 deny log any to me
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