Re: passive mode ftp high ports driving me nuts

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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:

# ftp passive mode (browser) stuff. Note: ftp_conntrack module is required, e.g.:
# /etc/sysconfig/iptables-config:
# IPTABLES_MODULES="ip_conntrack_ftp"
#
$tbls -A dsl-out -o eth1 -p tcp -s $eth1_addr --sport $unassgn --dport ftp -m state --state NEW,ESTABLISHED -j ACCEPT $tbls -A dsl-in -i eth1 -p tcp ! --syn --sport ftp -d $eth1_addr --dport $unassgn -m state --state RELATED,ESTABLISHED -j ACCEPT $tbls -A dsl-for -i eth1 -p tcp ! --syn --sport ftp -d $internal_net --dport $unassgn -m state --state RELATED,ESTABLISHED -j ACCEPT # The "ftpdata" session is a "new" one when it sends the SYN. However, the ftp_conntrack module marks it as related to its controlling # ftp session, so that state=related matches. This should deny any "ftpdata" session that doesn't have a controlling ftp session. #$tbls -A dsl-out -o eth1 -p tcp -s $eth1_addr --sport $unassgn -d $ANY_IP --dport $unassgn -m state --state RELATED,ESTABLISHED -j ACCEPT #$tbls -A dsl-in -i eth1 -p tcp ! --syn -s $ANY_IP --sport $unassgn -d $eth1_addr --dport $unassgn -m state --state RELATED,ESTABLISHED -j ACCEPT #$tbls -A dsl-for -i eth1 -p tcp ! --syn -s $ANY_IP --sport $unassgn -d $internal_net --dport $unassgn -m state --state RELATED,ESTABLISHED -j ACCEPT $tbls -A dsl-out -o eth1 -p tcp -s $eth1_addr -d $ANY_IP -m helper --helper ftp -m state --state RELATED,ESTABLISHED -j ACCEPT $tbls -A dsl-in -i eth1 -p tcp ! --syn -s $ANY_IP -d $eth1_addr -m helper --helper ftp -m state --state RELATED,ESTABLISHED -j ACCEPT $tbls -A dsl-for -i eth1 -p tcp ! --syn -s $ANY_IP -d $internal_net -m helper --helper ftp -m state --state RELATED,ESTABLISHED -j ACCEPT


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