Subject: INIT from private IP address to public IP address never received

From: "Eng Se-Hsieng" <[email-masked]>
Date: Wed, 30 Apr 2003 12:35:37 +0800

Dear all,

I have tried the following scenario using the Reference Implementation
with actual existing networks. Host A is on a GPRS network and Host B is
on a university network and is assigned a fixed IP.

Results using the University of Essen's implementatino were very
similar.

Host A (private IP 172.18.56.36) towards Host B (fixed IP
137.132.165.205)

traceroute returns 9 hops, then about 10 ***, without actually
terminating at Host B. However, Host A can ping and ftp Host B.

Using the Reference Implementation,
Host A: The log /usr/tmp/sctpclient shows an INIT chunk being
formulated. Ethereal logs show the INIT chunk being repeatedly sent.
Host B: The log /tmp/sctpDeamon does not show anything being received.

SCTP associations were previously successfully set up between Host B and
another machine internal to Host B's network (172.x.x.x).

1 We feel that the packet should at least arrive at the host, since it
should be pure IP routing. Since it's not showing up in the sctpDeamon
logs, is there any way to know if it actually arrived?

2. Might there be any SCTP servers we could try to initialise a SCTP
connection using our private IP client?

3. Have there been any instances where SCTP has been known to work from
behind a NAT?

Thank you.

Regards,
Se-Hsieng