From: "Michael K" <micke@klintan.se>
To: 'Budai Laszlo' <lbudai@ms.sapientia.ro>, netfilter@lists.netfilter.org
Subject: RE: ip_conntrack_ftp problem
Date: Fri, 28 Mar 2003 09:50:25 +0100 [thread overview]
Message-ID: <000001c2f507$13816ae0$0200a8c0@klintan.local> (raw)
In-Reply-To: <3E83FC78.7080801@ms.sapientia.ro>
> -----Original Message-----
> From: netfilter-admin@lists.netfilter.org
> [mailto:netfilter-admin@lists.netfilter.org] On Behalf Of Budai Laszlo
> Sent: Friday, March 28, 2003 8:41 AM
> To: netfilter@lists.netfilter.org
> Subject: ip_conntrack_ftp problem
>
>
>
>
> we use Redhat Linux 8 to connect our lan to the internet.
> Internally we
> are using private addresses which are SNAT-ed (MASQUERADE) by
> the linux box.
>
> We set up a firewall which in the forward chain looks like:
>
> Chain FORWARD (policy ACCEPT)
> target prot opt source destination
> ACCEPT all -- anywhere anywhere
> state RELATED
> ACCEPT tcp -- 192.168.101.25 anywhere
> tcp dpt:telnet
> ACCEPT tcp -- 192.168.101.24 anywhere
> tcp dpt:telnet
> ACCEPT tcp -- 192.168.101.0/24 anywhere
> tcp dpt:ldap
> ACCEPT tcp -- 192.168.101.0/24 anywhere
> tcp dpt:imap
> ACCEPT tcp -- 192.168.101.0/24 anywhere
> tcp dpt:rtsp
> ACCEPT tcp -- 192.168.101.0/24 anywhere
> tcp dpt:cvspserver
> ACCEPT tcp -- 192.168.101.0/24 anywhere
> tcp dpt:cvspserver
> ACCEPT tcp -- 192.168.101.0/24 anywhere
> tcp dpt:5190
> ACCEPT tcp -- 192.168.101.0/24 anywhere
> tcp dpt:squid
> ACCEPT tcp -- 192.168.101.0/24 anywhere
> tcp dpt:https
> ACCEPT udp -- 192.168.101.0/24 anywhere
> udp dpt:domain
> ACCEPT udp -- 192.168.101.0/24 anywhere
> udp dpt:7070
> ACCEPT tcp -- 192.168.101.0/24 anywhere
> tcp dpt:7070
> ACCEPT tcp -- 192.168.101.0/24 anywhere
> tcp dpt:https
> ACCEPT tcp -- 192.168.101.0/24 anywhere
> tcp dpt:5050
> ACCEPT tcp -- 192.168.101.0/24 anywhere
> tcp dpt:pop3
> ACCEPT tcp -- 192.168.101.0/24 anywhere
> tcp dpt:http
> ACCEPT tcp -- 192.168.101.0/24 anywhere
> tcp dpt:domain
> ACCEPT tcp -- 192.168.101.0/24 anywhere
> tcp dpt:smtp
> ACCEPT tcp -- 192.168.101.0/24 anywhere
> tcp dpt:ssh
> ACCEPT tcp -- 192.168.101.0/24 anywhere
> tcp dpt:ftp
> ACCEPT tcp -- 192.168.101.0/24 anywhere
> tcp dpt:ftp-data
> DROP tcp -- 192.168.101.0/24 anywhere
>
>
> so we try to limit the access just to a few accepted services. We are
> loading the ip_conntrack_ftp and ip_nat_ftp modules:
>
> # lsmod
> Module Size Used by Not tainted
> ipt_state 1080 1 (autoclean)
> cls_u32 6332 2 (autoclean)
> sch_cbq 14912 2 (autoclean)
> ip_nat_ftp 4240 0 (unused)
> ip_conntrack_ftp 5088 0 (unused)
> eepro100 22264 1
> 8139too 17736 1
> mii 2156 0 [8139too]
> iptable_mangle 2776 1 (autoclean)
> ipt_MASQUERADE 2200 0 (autoclean)
> ipt_REDIRECT 1368 3 (autoclean)
> iptable_nat 19960 2 (autoclean) [ip_nat_ftp
> ipt_MASQUERADE ipt_REDIRECT]
> ip_conntrack 21244 3 (autoclean) [ipt_state
> ip_nat_ftp ip_conntrack_ftp ipt_MASQUERADE ipt_REDIRECT iptable_nat]
> iptable_filter 2412 1 (autoclean)
> ip_tables 15224 8 [ipt_state iptable_mangle
> ipt_MASQUERADE ipt_REDIRECT iptable_nat iptable_filter]
> mousedev 5524 0 (unused)
> keybdev 2976 0 (unused)
> hid 22244 0 (unused)
> input 5920 0 [mousedev keybdev hid]
> usb-uhci 26188 0 (unused)
> usbcore 77024 1 [hid usb-uhci]
> ext3 70336 3
> jbd 52212 3 [ext3]
> sym53c8xx 68240 4
> sd_mod 13552 8
> scsi_mod 107176 2 [sym53c8xx sd_mod]
>
>
> but ftp trough the firewall still does not work. :(
> what is wrong?
>
> Thanks,
> Laszlo
>
I'm sure that active ftp works. Active FTP uses port TCP/20 for data
channel. Passive ftp uses > TCP/1023
So
Active FTP uses TCP port 21 and 20
Passive FTP uses TCP port 21 and > 1023
/Klintan
next prev parent reply other threads:[~2003-03-28 8:50 UTC|newest]
Thread overview: 13+ messages / expand[flat|nested] mbox.gz Atom feed top
2003-03-28 7:40 ip_conntrack_ftp problem Budai Laszlo
2003-03-28 8:27 ` Vincent Lim
2003-03-28 9:43 ` Budai Laszlo
2003-03-28 10:19 ` Vincent Lim
2003-03-28 10:43 ` Cedric Blancher
2003-03-28 10:59 ` Vincent Lim
2003-03-28 17:06 ` Cedric Blancher
2003-03-28 12:17 ` Jozsef Kadlecsik
2003-03-28 12:46 ` Cedric Blancher
2003-03-28 14:10 ` Jozsef Kadlecsik
2003-03-28 8:50 ` Michael K [this message]
-- strict thread matches above, loose matches on Subject: below --
2003-03-28 12:44 blancher
2003-03-28 12:45 blancher
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