RE: Problem with FreeBSD 4.8, ipf, ipfnat and forwarding for pcAnywhere

From: JJB (Barbish3_at_adelphia.net)
Date: 05/07/04

  • Next message: Daniel Bye: "buildworld failed"
    To: "adp" <dap99@i-55.com>, <questions@freebsd.org>
    Date: Fri, 7 May 2004 08:47:22 -0400
    
    

    For your telnet test to pcanywhere ports on target Lan pc to work
    you have to tell telnet on the target to listen on those ports.

    I believe pcanywhere is one of those applications that imbed the ip
    address of the remote and host into the packet data and used by the
    application to establish bi-directional packet exchange. This means
    that pcanywhere will not work using nated ip address. This is an
    common design flaw in many 3rd party software providers
    applications, mostly seen in games and ms/windows netmeeting.
    Pcanywhere only works over the public internet between two ms/window
    boxs that use public routable IP address. It will also work between
    two pc on the Lan because Nating only occurs as packet leaves Lan
    headed for public internet.

    If you have an range of static public IP address assigned to you by
    your ISP then you could assign one of those ip address to the LAN pc
    you want pcanywhere to work on and you should be good to go.

    -----Original Message-----
    From: owner-freebsd-questions@freebsd.org
    [mailto:owner-freebsd-questions@freebsd.org]On Behalf Of adp
    Sent: Friday, May 07, 2004 12:37 AM
    To: questions@freebsd.org
    Subject: Problem with FreeBSD 4.8, ipf, ipfnat and forwarding for
    pcAnywhere

    This shouldn't be that hard, but I can't get it working.

    I have a FreeBSD firewall with three NICs (Internet, LAN, DMZ). I
    have
    bridging enabled between the Internet and DMZ interfaces.

    I now have an internal computer (LAN) that needs to be accessible
    via
    pcAnywhere.

    I can telnet to the pcAnywhere ports on the internal computer fine
    from the
    firewall or the LAN. So that works. However, when I configured ipnat
    to
    forward my pcAnywhere ports a telnet from the Internet just stalls.

    My ipnat configuration:

    # cat /etc/ipnat.conf

    (xl0 = internet, xl1 = lan, xl2 = dmz)

    ####################
    # pcAnywhere
    # normal nat for office disabled - this is all i have in ipnat.conf
    rdr xl0 public-ip/32 port 5631 -> 192.168.99.9 port 5631
    rdr xl0 public-ip/32 port 5632 -> 192.168.99.9 port 5632

    And I am allowing in accessing via ipf:

    pass in quick proto tcp from any to public-ip port = 5631 group 200
    pass in quick proto udp from any to public-ip port = 5631 group 200
    pass in quick proto tcp from any to public-ip port = 5632 group 200
    pass in quick proto udp from any to public-ip port = 5632 group 200

    (If I take these out I see the ipmon block messages, but with these
    they go
    away, so it's not ipf I don't think.)

    Am I missing something here? This should work!

    A tcpdump. I am remote (remote-client):

    %telnet public-ip 5631
    Trying public-ip...

    (just sits there)

    On the FreeBSD box:

    # tcpdump -n -i xl0 port 5631
    tcpdump: listening on xl0
    23:26:41.772801 remote-client.3755 > public-ip.5631: S
    2174885259:2174885259(0) win 57344 <mss 1460,nop,wscale
    0,nop,nop,timestamp
    99416198 0> (DF) [tos 0x10]
    23:26:44.772018 remote-client.3755 > public-ip.5631: S
    2174885259:2174885259(0) win 57344 <mss 1460,nop,wscale
    0,nop,nop,timestamp
    99416498 0> (DF) [tos 0x10]
    23:26:48.013346 remote-client.3755 > public-ip.5631: S
    2174885259:2174885259(0) win 57344 <mss 1460,nop,wscale
    0,nop,nop,timestamp
    99416818 0> (DF) [tos 0x10]
    23:26:51.230241 remote-client.3755 > public-ip.5631: S
    2174885259:2174885259(0) win 57344 <mss 1460> (DF) [tos 0x10]
    23:26:54.429267 remote-client.3755 > public-ip.5631: S
    2174885259:2174885259(0) win 57344 <mss 1460> (DF) [tos 0x10]
    23:26:57.596288 remote-client.3755 > public-ip.5631: S
    2174885259:2174885259(0) win 57344 <mss 1460> (DF) [tos 0x10]
    23:27:03.809921 remote-client.3755 > public-ip.5631: S
    2174885259:2174885259(0) win 57344 <mss 1460> (DF) [tos 0x10]
    23:27:16.050057 remote-client.3755 > public-ip.5631: S
    2174885259:2174885259(0) win 57344 <mss 1460> (DF) [tos 0x10]
    ^C
    48 packets received by filter
    0 packets dropped by kernel

    Oh, and again, I do have bridging enabled between Internet and DMZ:

    My bridge script:

    #!/bin/sh

    echo -n "Enabling bridging: "
    if sysctl -w net.link.ether.bridge=1 > /dev/null 2>&1; then
            echo "activated."
    else
            echo "failed."
    fi

    echo -n "Enabling bridging between xl0 and xl2 interfaces: "
    if sysctl -w net.link.ether.bridge_cfg=xl0,xl2 > /dev/null 2>&1;
    then
            echo "activated."
    else
            echo "failed."
    fi

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  • Next message: Daniel Bye: "buildworld failed"

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