RE: spoofed packets to RFC 1918 addresses

From: Sterling, Chuck (csterlinat_private)
Date: Fri Jun 28 2002 - 07:27:21 PDT

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    FWIW, how does one get the various Internet widgets to route packets
    addressed to 192.168.*, especially to a different network? I was under the
    impression that they were unroutable over the Internet. Is this incorrect,
    or is someone messing with routing tables somewhere, or what? If this is
    taking place I need some more education... probably do anyway.
    
    The reason I ask is that when I see packets with 192.168.* or other
    similarly defined addresses, it is invariably as a source address, and I
    assume that, if it was done intentionally, the sender does not really expect
    an answer (to an unroutable (?) address). So far as I know there have been
    no inbound external packets addressed _to_ 192.168.*. If I saw some within
    my net, I would hunt within my net for the transmitter. An example of this
    is some leakage from a small SAN we have that uses 10.* addresses
    internally. Occasionally I would see some of those hit the internal side of
    the firewall, and after tracing them I found that more-or-less legitimate
    source for them.
    
    Chuck Sterling
    Magic is REAL, unless declared INTEGER
    
    > ----------
    > From: 	HggdH[SMTP:hggdhat_private]
    > Sent: 	Thursday, June 27, 2002 4:05 PM
    > To: 	Incidents
    > Subject: 	Fw: spoofed packets to RFC 1918 addresses
    > 
    > I wonder ... I just remembered that at least the Linksys DSL/Cable
    > routers,
    > by default, sit at 192.168.1.x; the DMZ is, usually, on the same subnet.
    > 
    > Would someone be looking for Windows hosts there? As Linksys puts it, a
    > machine in the DMZ is completely exposed to the Internet. No firewall
    > protection.
    > 
    > ..hggdh..
    > ----- Original Message -----
    > From: "Robert E. Lee" <relat_private>
    > (snip)
    > My organization saw some connection attempts to an rfc1918 space on our
    > firewall in the past few days as well.  Specifically ip's in the
    > 192.168.1.0/24 space, and specifically on tcp port 137.  The firewall
    > marked the packets as being spoofed, and dropped them.
    > (snip)
    > 
    > 
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