On 09.01.2010 14:55, Mart Frauenlob wrote: > On 09.01.2010 03:59, MargoAndTodd wrote: >> On 01/08/2010 02:24 AM, Mart Frauenlob wrote: >> >>>> It is the "--sport $unassgn --dport $unassgn" that is killing me. >>>> How do I restrict the last three to just passive mode ftp? >>>> >>> >>> use the 'helper' match extension. i.e: -m helper --helper ftp. >>> if you need to distinguish between active and passive, you still can use >>> the port and state matches for that. >> >> Hi Mart, >> >> Works perfectly. Thank you! >> >> -T >> >> p.s. my new rules: >> [...] > > if you use user-defined chains (which is good), take full advantage of > it, by not repeating so many values in your ruleset. i.e. dsl-in will > always have -i eth1 and -d $eth1_addr. > you don't need -d $ANY_IP, just leave it out, gives the same result. > you don't need --syn, if you rely on conntrack helper match. > > let me suggest a more structured approach: > [...] > > as an untested example with some additional design considerations for > invalid packets and related icmp. > sorry had the naming for dsl-for and dsl-fwd mixed up, again corrected: # assuming DROP policy for INPUT,OUTPUT,FORWARD... for x in dsl-in dsl-out dsl-for invalid; do $ipt -N $x done # sort out the illegal packets - could add more eventually... $ipt -A invalid -p tcp ! --syn -m state --state NEW -j DROP $ipt -A invalid -m state --state INVALID -j DROP # global rules: # allow established - speed up processing by placing rule on top # then sort out bad ones # allow related icmp for x in INPUT OUTPUT FORWARD; do $ipt -A $x -m state ESTABLISHED -j ACCEPT $ipt -A $x -j invalid $ipt -A $x -p icmp -m state --state RELATED -j ACCEPT done # allow the related ftp packets for x in dsl-in dsl-out dsl-for; do $ipt -A $x -m helper --helper ftp -j ACCEPT done # allow new outgoing ftp connections $ipt -A dsl-out -p tcp --dport 21 -m state --state NEW -j ACCEPT $ipt -A dsl-for -s $internal_net -p tcp --dport 21 -m state --state NEW -j ACCEPT # jump tree $ipt -A INPUT -i eth1 -d $eth1_addr -j dsl-in $ipt -A OUTPUT -o eth1 -s $eth1_addr -j dsl-out $ipt -A FORWARD -i eth1 -d $internal_net -j dsl-for $ipt -A FORWARD -o eth1 -s $internal_net -j dsl-for -- To unsubscribe from this list: send the line "unsubscribe netfilter" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
