Date: Thu, 31 Mar 2005 09:31:07 +0200 From: Hexren <me@hexren.net> To: Jayel Villamin <jarthel@gmail.com> Cc: freebsd-pf@freebsd.org Subject: Re: weird PF behavior Message-ID: <1571611907.20050331093107@hexren.net> In-Reply-To: <b2d2a52705033022181ea45294@mail.gmail.com> References: <b2d2a52705033022181ea45294@mail.gmail.com>
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> Here's a rough sketch of the home network
FBSD 5.3 box ===>>>> xl0 ===>>> ADSL modem
> ===>>> xl1 ===>>> 10/100 Mbps switch ===>>>
> several Windows PC are connected to the switch
> ===>>> xl2 ===>>> Windows PC (via x-over cable).
> This is the FTP server.
> I have an FTP server running in a windows box with IP = 192.168.2.2
> here's a snippet of my rules
> ==========
> ext_if = "tun0"
> elayne_ftp_service = "19985:19989"
> elayne = "192.168.2.2/32"
> rdr on $ext_if proto tcp from any to ($ext_if) port
> $elayne_ftp_service -> $elayne
> block log all #This is the very first rule after the nat/rdr rules
> pass in quick on $ext_if inet proto tcp from any to $elayne port {
> $elayne_ftp_service } flags S/SA keep state
> ============
> Looking at the PF FAQ in openbsd.org, this seem to be correct.
> But when I try to connect from work to the FTP, I get the following
> tcpdump entries:
> =====================
> 15:44:38.009604 IP SOURCE_IP_HIDDEN_FOR_PRIVACY.43318 >
> TARGET_IP_HIDDEN_FOR_PRIVACY.19989: S 1052116979:1052116979(0) win
> 49640 <mss 1402,nop,nop,sackOK>
> 15:44:41.423697 IP SOURCE_IP_HIDDEN_FOR_PRIVACY.43318 >
> TARGET_IP_HIDDEN_FOR_PRIVACY.19989: S 1052116979:1052116979(0) win
> 49640 <mss 1402,nop,nop,sackOK>
> ===================
> If I change the last rule in the snippet to:
> ===========
> pass in quick inet proto tcp from any to $elayne port {
> $elayne_ftp_service } flags S/SA keep state
> ===========
> it works.
> Well I thought that having "on $ext_if" is correctly as well as the
> traffic from work to home FTP server must pass thru $ext_if.
> Any ideas for this behavior?
> Thanks
---------------------------------------------
Guessing I would say that:
The traffic comes in on $ext_if a state for it is created and it then
tries to leave over $int_if. At that point it is catched by "block log
all #This is the very first rule after the nat/rdr rules" as obviously
"on $ext_if" in the pass rule. Is not true for a packet traversing
$int_if. Imho a rule alog the lines of "pass on $int_if from any to
$elayne port { $elayne_ftp_service } keep state" should fix the
problem. Try it I am not dead sure.
Regards
Hexren
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