Re: Best way to deal with long opened sessions

[Stefano Mtangoo <mwinjilisti@xxxxxxxxx>]

Thanks Tilo for the comment.
Its seems there is no simple way and your detailed explanations is
invaluable.

If anyone else feels to add anything, I would be honored.
Regards,
Stefano

On Thu, Mar 14, 2019 at 1:23 PM Tilo Eckert <tilo.eckert@xxxxxxx> wrote:

> Hi Stefano,
>
> ssh_is_connected() returns session->alive which is only set to 0 when
> the client or server explicitly disconnects or the handshake fails.
>
> If your connection silently dies, you can only notice this when you send
> anything to the server and it does not respond within some time frame.
> If you configured a libssh timeout, most blocking functions will return
> SSH_ERROR when the server does not respond to your request. You would
> still have to call ssh_disconnect() yourself because a timeout does not
> necessarily mean that the remote host is gone.
>
> If you leave your connection open for longer periods of time without
> interacting with the server, you will not notice a silently broken
> connection until you send something to the server and wait for its
> reply. If you want to detect broken connections even while idling, you
> should probably enable TCP keep-alive packets by enabling SO_KEEPALIVE
> on the socket:
> > socket_t socket = ssh_get_fd(session);
> > int yes = 1;
> > if (setsockopt(socket, SOL_SOCKET, SO_KEEPALIVE, &yes, sizeof(int)) < 0)
> {
> >   // setting SO_KEEPALIVE failed
> > }
>
> It will cause your OS kernel to automatically send keep-alive TCP
> packets every now and then (configurable on Linux via TCP_KEEPIDLE,
> TCP_KEEPINTVL, TCP_KEEPCNT socket options). This is transparent to your
> application. If the server does not respond for some time (Linux kernel
> default: 30 minutes), the TCP socket is closed by the kernel. To notice
> the latter, the socket must be polled. So, you need to regularly call
> any libssh function that reads from or writes to the socket and check if
> that fails.
>
> Best regards
> Tilo Eckert
>
> Am 14.03.2019 um 07:57 schrieb Stefano Mtangoo:
> > Hi,
> > This library have made my life simpler and would like to thank everyone
> > involded.
> > I have one thing that I would like to get your advice on. I keep my
> > session long open when I edit something on the server. During those long
> > time network can be lost and be restored.
> >
> > Is checking for `ssh_is_connected` alone enough?
> > I use SFTP module to connect to the server and edit stuffs and ssh_* for
> > everything else.
> > Regards,
> > Stefano
> > --
> > for me to live is Christ to die is gain
>
>
>

-- 
for me to live is Christ to die is gain