Re: Is ssh appropriate for this use case?

[Christopher Morley <chris@xxxxxxxxxxxxxxx>]

Hello Yuanzhe,
Thank you for your reply and the links, I will study them.
Best regards,
Chris


On Fri, Apr 10, 2020 at 3:58 AM 刘元哲 <945695107@xxxxxx> wrote:

> Hello, Chris
>
> I'm also learning libssh this few days, and found your problem when I wake
> up at afternoon :-).
> First of all, I think libssh tcp/ip forwarding can solve your problem, u
> need read
> https://blog.trackets.com/2014/05/17/ssh-tunnel-local-and-remote-port-forwarding-explained-with-examples.html(local
> port forwarding part) to understand what  does local port forwarding do and
> why it's an appropriate solution.
> Then u can read this
> https://api.libssh.org/stable/libssh_tutor_forwarding.html
> It shows the whole architecture about tcp/ip forward on client side. It
> holds one session between client(java) and server(c++),
> no matter how many simulation processes u have, it doesn't care. I'm not
> familiar with java, but libssh is used in C, maybe
> u need a JNI? Anyway once u can run this function, the server
> side(sshd_tcpip_forward.c), should be able to receive the request.
> Here to make things clear, libssh is not something u can use automatic,
> it's NOT openssh, a prebuilt binary with many options u can choose,
> u need to program some codes:
> the client side in tutor only show how to open a request to server, I
> think u need to make java part connect to some localhost port, see 4321,
> then in client code, u program a event_loop, check here:
> https://api.libssh.org/stable/group__libssh__poll.html, ssh_add_event_fd,
> use socket to listen at 4321, once something arrive, forward it to server.
> Obviously u need to define what the date struct, as u may have many
> simulation processes, and how long it is.(read ssh_channel_open_forward
> CAREFULLY!!, u must understand what the parameter should be).
> Now it's ready to send it, once server receive it, it also need to
> re-direct to ur cpp listen port, here u also need program with socket, like
> client side,
> use ssh_event callback.
>
> Hope my thought can inspire you,
> And sorry for the bad typesetting
> Yuanzhe
>
> ------------------ 原始邮件 ------------------
> *发件人:* "Christopher Morley"<chris@xxxxxxxxxxxxxxx>;
> *发送时间:* 2020年4月10日(星期五) 上午8:07
> *收件人:* "libssh"<libssh@xxxxxxxxxx>;
> *主题:* Is ssh appropriate for this use case?
>
> Hi all -
> I hope this is an appropriate question for this forum.
>
> I have an application that consists of a user interface component (written
> in java) and a simulation engine (written in c++). These run in separate
> processes, potentially on different machines. The java process can start
> one or more simulation processes, disconnect, and re-connect to them. The
> simulation process can accept multiple user interface connections.
> Currently the processes communicate via tcp sockets, with the c++ process
> implementing a fairly standard non-blocking select-based event loop for
> processing requests from the connected java process(es).
>
> I would like to add user authentication (for connection requests to the
> c++ simulation component) and encryption of the socket communications. I
> have been working on a small prototype based on the sshd_direct-tcpip.c
> example from libssh and the jsch example app UserAuthPubKey.java using
> public key (RSA) authentication.
>
> OK, my specific questions:
> 1. Is ssh in general and libssh (and jsch?) appropriate choices to solve
> this problem?
> 2. Is the direct-tcpip channel the right one to use? Is there a more
> appropriate example that I can use, such as an "echo" server?
> 3. If there is not such an example, would offering $ persuade anyone to
> produce such an example (eg a non-blocking echo server using libssh) ?
>
> Thanks in advance for any assistance or opinions you can offer-
> Chris
>
>