TCP/IP Packet Question

Dear Linux Network Gurus,

I have a question. Is it possible to send a tcp/ip packet accros the
network without a return address? (does that even sound right?) I would
like some data to go 1 way, without knowing where it came from. I don't
know of anything else to ask about this.... so.... any help would be very
greatly appreciated.

thanks ryan

Ryan Howell <(E-Mail Removed)> wrote:
> I have a question. Is it possible to send a tcp/ip packet
> accros the network without a return address?

No.

TCP segments are carried in IP datagrams, and IP datagrams have source
IP addresses in them. That is not to say that one cannot use a bogus
source IP address (modulo ISP filtering source IP addresses on the
ingress points of their networks), but running a TCP connection from a
forged IP address is a difficult thing to do. You have to be able to
either recieve or correctly guess the TCP segments that will be coming
the other way (to the bogus IP address). Not impossible, but not
necessarily trivial.

Even if you then say ditch TCP and use UDP, to get a UDP datagram to
anyone you need a valid destination IP address - either a unicast or
perhaps a multicast. That then defines a starting point (the
endpoint) for a search. Even if you put a bogus source IP address in
the IP datagram carrying the UDP datagram, someone sufficiently
motivated can still start tracing wires back from the destination
until they find the ingress point for the IP traffic.

The whole thing is rather more complicated than that, but still the
basic answer is that one cannot remain completely anonymous on the net
indefinitely so long as someone else wants badly enough to find-out.

rick jones
--
oxymoron n, Hummer H2 with California Save Our Coasts and Oceans plates
these opinions are mine, all mine; HP might not want them anyway...
feel free to post, OR email to raj in cup.hp.com but NOT BOTH...

Ryan Howell wrote:
> Dear Linux Network Gurus,
>
> I have a question. Is it possible to send a tcp/ip packet accros the
> network without a return address? (does that even sound right?) I would
> like some data to go 1 way, without knowing where it came from. I don't
> know of anything else to ask about this.... so.... any help would be very
> greatly appreciated.
>
> thanks ryan

spoof

I believe it is impossible with TCP/IP
You also have the ack-nr (used for giving a notion of wich packets were
accepted by the receiver) in the IP Datagram.
They are sent to de senders ip.
If the senders ip ins't the correct one the sender will keep sending the
same pakket (handshake) over and over...

I believe it is possible with UDP...

Greetz Matata


"Rick Jones" <(E-Mail Removed)> wrote in message
news:SMkUa.933$(E-Mail Removed)...
> Ryan Howell <(E-Mail Removed)> wrote:
> > I have a question. Is it possible to send a tcp/ip packet
> > accros the network without a return address?
>
> No.
>
> TCP segments are carried in IP datagrams, and IP datagrams have source
> IP addresses in them. That is not to say that one cannot use a bogus
> source IP address (modulo ISP filtering source IP addresses on the
> ingress points of their networks), but running a TCP connection from a
> forged IP address is a difficult thing to do. You have to be able to
> either recieve or correctly guess the TCP segments that will be coming
> the other way (to the bogus IP address). Not impossible, but not
> necessarily trivial.
>
> Even if you then say ditch TCP and use UDP, to get a UDP datagram to
> anyone you need a valid destination IP address - either a unicast or
> perhaps a multicast. That then defines a starting point (the
> endpoint) for a search. Even if you put a bogus source IP address in
> the IP datagram carrying the UDP datagram, someone sufficiently
> motivated can still start tracing wires back from the destination
> until they find the ingress point for the IP traffic.
>
> The whole thing is rather more complicated than that, but still the
> basic answer is that one cannot remain completely anonymous on the net
> indefinitely so long as someone else wants badly enough to find-out.
>
> rick jones
> --
> oxymoron n, Hummer H2 with California Save Our Coasts and Oceans plates
> these opinions are mine, all mine; HP might not want them anyway...
> feel free to post, OR email to raj in cup.hp.com but NOT BOTH...