> I want to know , where can I found the TCP-Clear protocol ( RFC ??, flow
> control ).
Well, a search for "TCP clear" in Google found
http://www.vircom.com/en/products/vopradius/docs_vopradius/text_db_vopradius.shtml
which says
Remote Host Information
When a user's Service-Type is Login-User, two pieces of
information may be supplied: the service used to connect to the
host, and the name or IP address of the remote host. A TCP port
number may optionally be supplied.
To specify the login service, use the Login-Service reply item.
Login-Service values are:
Telnet
Establishes a Telnet connection to the remote host.
Rlogin
Establishes an Rlogin connection to the remote host.
TCP-Clear
Establishes a TCP clear connection to the remote host. 8-bit
data is passed through this connection without interpretation.
This option is the equivalent of the netdata login service on
the PortMaster.
PortMaster
Establishes a connection to the remote host using the PortMaster
login service. To use this setting, the in.pmd daemon must be
installed on the remote host.
which suggests that the "protocol" is null - i.e., every single byte
passed to the remote host from the client gets turned into pseudo-tty
input on the host, and every single byte that goes out the pseudo-tty on
the host goes out unchanged ove the wire to the client.
> TCP-Clear tunnels can be established for SLIP, asynchronous and PPP
> connections. TCP-Clear tunnels are
> similar to L2TP tunnels, but I don't know the differences.
It may, on some Web pages I've seen, mention it in conjunction with
L2TP, but the stuff I've seen seems to at least suggest that "clear"
means "clear" as in "just sends raw data over a TCP connection".
