Re: Controlling ports used by natd

From: Barney Wolff (barney_at_databus.com)
Date: 12/12/03

  • Next message: Helge Oldach: "Re: ssh tunnels and Xvnc - (yes, I know... What? not again!?)" 
    Date: Fri, 12 Dec 2003 03:35:22 -0500
To: Brett Glass <brett@lariat.org>

    On Fri, Dec 12, 2003 at 01:19:34AM -0700, Brett Glass wrote:
    > At 12:45 AM 12/12/2003, Barney Wolff wrote:
    >
    > >UTSL libpcap/alias_db.c
    >
    > I can find no such file in /usr/src/contrib/libpcap. I did find
    > one in /usr/src/lib/libalias. It seems to have in it a function
    > called FindNewPortGroup that hunts for ports at random, but
    > there's no discipline there to make it avoid specific ports
    > or groups of ports. Are you suggesting that I modify this
    > function to add port exclusion as a new feature? I suppose that
    > I could do this, but it would involve changing data structures
    > that were used by many programs, including natd and ppp. So,
    > there could be a huge ripple effect.

    Oops, sorry for the confusion. How fancy a change is up to you,
    but changing ALIAS_PORT_BASE and ALIAS_PORT_MASK (and _EVEN)
    would let you confine the port range without much work. Un-nat'd
    folks are most likely using ports in the hi range, and usually
    without trouble - presumably normal programs don't make special
    checks for trojan ports. 

    -- 
Barney Wolff         http://www.databus.com/bwresume.pdf
I'm available by contract or FT, in the NYC metro area or via the 'Net.
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