Re: NATD and Address Redirection

From: Jim Durham (durham_at_jcdurham.com)
Date: 07/27/03

  • Next message: Jim Durham: "Re: NATD and Address Redirection"
    To: Yar Tikhiy <yar@comp.chem.msu.su>
    Date: Sat, 26 Jul 2003 22:26:55 -0400
    
    

    On Saturday 26 July 2003 03:42 am, Yar Tikhiy wrote:
    > On Fri, Jul 25, 2003 at 01:49:38PM -0400, Jim Durham wrote:
    > > The procedure we used was to alias a 2nd public address to the
    > > outside interface and use a redirect_address statement in
    > > natd.conf to redirect connections to the new public IP to the
    > > inside machine.
    >
    > Just a remark: If this 2nd public IP is already routed to your
    > gateway, you don't need to add it as an alias for your gateway's
    > outside interface. But you really need to if the latter interface
    > is on a broadcast network and must do ARP to attract packets
    > destined to the 2nd public IP specified to natd.

    Ok... it's sitting on the back side of a Cisco on a class C public. It
    doesn't sound like this would prevent anything from working in any
    case.
    >
    > > This doesn't seem to be symmetrical. You can ping the inside
    > > machine from outside using the new address and if you connect
    > > outwards from the inside machine, the outside world sees the
    > > connection as coming form the new public IP. However, a test
    > > running VNC server on the inside machine and connecting from
    > > outside does not work. You can connect to the inside machine and
    > > it sees mouse and keyboard, but the virtual screen does not work.
    > > It seems that the connection works properly redirecting inward
    > > but not outward. VNC disconnects in about a minute.
    >
    > Could you check if TELNET, HTTP, or SSH from the outside world to
    > the inside machine works? The problem may have to do with VNC
    > protocol peculiarities preventing it from working through NAT.
    > (However, the VNC FAQ claims VNC will work through NAT.)

    Well, that was my suggestion to my partner. All the inside machines
    are M$ workstations, so no connectable services running on them
    That's why we installed VNC. I suggested that we get a *nix box on
    the inside network that we can actually *do* something useful with
    8-; .

    To further thicken the soup. This is not the only client system with a
    problem like this. There's another LAN client back of the NAT on a
    FreeBSD box that needs to run a piece of software that connects to
    some database system that figures out the most efficient routing for
    carrying loads on a semi trailer. We were running this guy very
    happily on an ISDN connection and using the NAt built into the PPP
    client. We tried to put him on a system hanging off a T1 line using
    natd and never got it to work. I did lots of tcpdumps on that using
    both the PPP nat and NATD and couldn't see any difference! However it
    worked just fine with the nat in PPP client, but not NATD. So, there
    may be a clue there.

    Another user is trying to run yahoo chat through NATD and no go, even
    with a redirect_address to her computer. I believe this also works on
    the PPP machine with the ISDN line, but not on NATD.

    So, my question is "What's the difference"? Is it different handling
    of icmp or something of that sort?

    -- 
    -Jim
    _______________________________________________
    freebsd-hackers@freebsd.org mailing list
    http://lists.freebsd.org/mailman/listinfo/freebsd-hackers
    To unsubscribe, send any mail to "freebsd-hackers-unsubscribe@freebsd.org"
    

  • Next message: Jim Durham: "Re: NATD and Address Redirection"

    Relevant Pages

    • Re: Processs PreciseMail AntiSpam Gateway - any experience so far ?
      ... Client sending system ... >> ISP using dynamic NAT with port overloading. ... >> 10.11.12.1 is the clients real address and it opens a connection from its port ...
      (comp.os.vms)
    • Re: WinRoute Pro
      ... If a RST is sent to a TCP protocol host, ... 1/ Check the NAT table. ... 2/ Open a TCP connection to a host using a port tool. ... Winroute's logs are no substitute for a decent packet sniffer. ...
      (comp.security.firewalls)
    • Re: Remote rebooting
      ... I'll bet you need to make a connection as administrator to the PC (using IPC$ as shown above) ... The machine is running under admin and I can add/modify/delete any files in any folder with either VNC or CuteFTP Pro. ... I can log in with CuteFTP PRO and do what I want with files etc. Seems odd to me that the ftp server is running yet apparently the Windows task manage isn't starting scheduled tasks. ... Even if I can't recover from this hang I need to setup a fool proof way to reboot this system. ...
      (microsoft.public.win2000.cmdprompt.admin)
    • Re: Remote Desktop Connection
      ... You can try a free two user version of SSL-Explorer to try it out. ... SSL-Explorer also supports a web based RDC and VNC access to desktop PCs on your network. ... OpenVPN is completely free like SSH. ... What if i have a linkys WiFi router, and does not have vpn feature, how could i secure the connection? ...
      (microsoft.public.windowsxp.work_remotely)
    • Re: Establish external trust over a NAT device
      ... suggesting hardware over Windows built-in functionality for a VPN solution. ... even a fairly cheap router will likely have much better throughput ... L2TP and routing over it with or without NAT on that connection. ...
      (microsoft.public.win2000.active_directory)