RE: iSCSI CONNECT message

[Joshua Tseng/Nishan Systems <joshua.tseng@NishanSystems.com>]

David,

>I think you are not correctly representing the world. None of telnet,
>ftp, or rlogin proxies/gateways include a hostname or other DNS name.
>All proxies are external out of band entities that do not have any
>in band protocol support. While http does have in-band data that proxies
>may use, strictly speaking it is not necessary for functionality it
>could be treated just like telnet or FTP. Because caching in http is
>so important, DNS names are passed around. E-mail is different though,
>while there are multiple gateways (MX records etc) and hops to
>deliver e-mail, each individual hop is a seperate SMTP session. E-mail
>is also designed to go over non-IP networks like UUCP so it is not
>compareable to iSCSI. (Storage over UUCP, what a concept! :-)

If I am "not correctly representing the world", it is purely
unintentional. But my references indicate that at least rlogin and
ftp embed the destination hostname in the messaging between
client and server (see TCP/IP Illustrated by R. Stevens, pg 396-397
and pg 428).  In rlogin, there are three strings sent after the
first byte--login name of the client, login name of server, and
terminal type and speed.  In ftp, the hostnames are passed in the
control connection.

The reference skips the detail on the description of telnet login,
but I assume that telnet is quite similar to rlogin, so it must
have it as well.

Additionally, my real-world experience with application proxy
firewalls indicate that this MUST be so, or the proxy firewall
should not be working!  Am I missing something here?  Otherwise,
how is it working???  I do not understand what you mean by "out
of band entities".

Josh

-----Original Message-----
From: David Robinson [mailto:David.Robinson@EBay.Sun.COM]
Sent: Monday, October 09, 2000 4:07 PM
To: ips@ece.cmu.edu
Subject: Re: iSCSI CONNECT message


Joshua Tseng/Nishan Systems wrote:
> I am not defining a tunnel in the sense of IP tunneling.  I think
> you are confused by Jim's discussion about explicit and implicit
> "tunneling"--we are talking about something different here.  What
> I am describing is no different from what exists today with http,
> telnet, ftp, rlogin, e-mail, and many other applications.  Each of
> these protocols has the hostname (DNS name) of the sending and
> receiving hosts imbedded in the protocol, for use by proxies when
> necessary. 

Josh,

I think you are not correctly representing the world. None of telnet,
ftp, or rlogin proxies/gateways include a hostname or other DNS name.
All proxies are external out of band entities that do not have any
in band protocol support. While http does have in-band data that proxies
may use, strictly speaking it is not necessary for functionality it
could be treated just like telnet or FTP. Because caching in http is
so important, DNS names are passed around. E-mail is different though,
while there are multiple gateways (MX records etc) and hops to
deliver e-mail, each individual hop is a seperate SMTP session. E-mail
is also designed to go over non-IP networks like UUCP so it is not
compareable to iSCSI. (Storage over UUCP, what a concept! :-)

In the vast majority of the cases for iSCSI, there will be either no
proxy/gateway/tunnel or it will be a simple firewall which is a well
understood problem. The other cases seem too few and too likely to
require an out of band management to bother complicating iSCSI.

	-David