From: Victor Reyes <victor.reyes@...>
Date: 2008-05-24T06:07:43+09:00
Subject: Need your recommendations for TCP Server/Client design

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Team,

Let me begin by stating that I am still a Ruby novice, although I've written
some simple appls (sudoku, TCP and UDP servers and other mundane appls) with
the input of the team.

I worked with AIX and I support more than a hundred servers in a complex and
secured??? environment.
Although some vendors have packages to perform "distributed" remote support,
it is not allowed in my environment.
At first tried to design my own poor-man distributed package using what is
allowed, ssh (port 22).
But this did not provide the flexibility to manage all the servers from one
centralized location.

So, I went ahead and designed in Ruby a TCP Client/Server that works as
follows:

On every server I have a server listening on a predefined port.
The server gets started from the cron and every 10 minutes the cron checks
to ensure that the server is running.

Lets say the client wants to execute a remote command like creating a userid
on all servers or just checking paging or memory consumption, etc.
It sends a request to the server and the server executes the command and
returns the output to the client.

So the client can:

dshc -s hostname cmd
dshc -p full_path_of_a_file_with_list_of_servers
dhsc -a cmd   (This version uses a file */etc/servers* with the list of all
servers)

I also have another client named *dshp* with the same flags as above and
which uses the same TCP server and which is listening on the same port.
The *dshp *program is used to *push* files to one or multiple or all
servers.

All the UNIX admin actually love the application. BTW, the *dshc  dshp* are
only executable by *root*.

However, although we are behind multiple firewalls (at least 6) a scanning
tool detected the listener (TCP Server) and marked it as a security risk on
a particular server.
I was asked and of course I complied, to shutdown the server on that host.
I was also asked to redesign the tool adding a bit more security and they
would allow it. They suggested "handshaking" between client and server, the
initial comm or perhaps all comm should be encrypted. I was asked if Ruby
has encryption
So here is where I am looking for some recommendations.

Reading a new book I just acquired I came across a package called *GServer*.
I was wondering if this will be suitable for what I need.
Also, what type of encryption should I use?

They were talking something like:

Client sends connection request
Server replies with client's *hostname* and *time*
Client sends back the *time *received from server together with the command
which the client wants to execute at the remote server.
Server executes command if it is "happy" with the reply from the client.

Of course all communication must be ciphered.

Any suggestions will be greatly appreciated.

Thank you

Victor

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