Mosh: add libutempter

[hgy59]

Motivation: This is a followup of the work started by @sn00pster (new account: @fizzyade)
Linked issues: #3583, closes #3582, closes #3583, #4820

Checklist

• Build rule all-supported completed successfully
• Package upgrade completed successfully
• New installation of package completed successfully

Remarks

As for #3583 no dedicated branch was created, it was not possible for me to make the fixes on the original branch.

[hgy59]

@sn00pster to work on #3583 (comment) I need to have a use case for detached sessions.
Any guidance on how to use mosh and how to detach sessions would be appreciated.

[fizzyade]

@sn00pster to work on #3583 (comment) I need to have a use case for detached sessions.
Any guidance on how to use mosh and how to detach sessions would be appreciated.

I’m not sure what you mean? Mosh allows the session to float between connections, unlike ssh where if the connection dies, the session is terminated.

I don’t use Synology equipment any more.

[hgy59]

I’m not sure what you mean? Mosh allows the session to float between connections, unlike ssh where if the connection dies, the session is terminated.

I don't know mosh at all (and didn't find any guidance)

• do I have to start the mosh server on the diskstation?
• what app do I need on a mobile (android) device?
• how do I connect (protocol, credentials)?

[fizzyade]

Mosh isn't a daemon.

When you want to open a mosh connection to a server, it actually ssh's into the target machine and then spawns the mosh command which either starts a new or attaches to an existing session, the ssh connection is closed, it's literally only used to initiate a session.

it uses utmp to handle the sessions, libutempter is used to list the target machines sessions, because mosh connections are persistent until you physically log the session out (sessions remain through disconnects), so of your client crashes or doesn't' save the state, the sessions will hang around on the target. utempter is used to list these on connection, so you know that they exist and that you can then close them.

No idea about an android client, I don't use android. I'm sure somebody has created or provided a mosh binary for it. I personally use iOS and the best client I've ever found is Blink, which is really good.

As above, sessions are initiated via ssh, mosh handles this for you. You need ssh to start the connection, once logged in and a mosh session is created using the mosh binary, the communication then goes via UDP.

[hgy59]

@fizzyade thank you very much for the detailed description.
So I will use mosh on my debian workstation and MobaXterm on windows to test mosh with a diskstation as I have no OSX device.

[ymartin59]

It is worth to submit this upstream to ease maintenance

[ymartin59]

@hgy59 Thanks. As far as I remember tmux may benefit from libutempter too.

[ymartin59]

@hgy59 I have rebased your branch to resolve conflict, test package and publish... but it looks like you have force-pushed back - reintroducing merge conflict I have resolved yesterday. Have you got changes I have not included yesterday? Do you mind to move to my rebased-resolved branch with git reset --hard?

[hgy59]

@hgy59 I have rebased your branch to resolve conflict, test package and publish... but it looks like you have force-pushed back - reintroducing merge conflict I have resolved yesterday. Have you got changes I have not included yesterday? Do you mind to move to my rebased-resolved branch with git reset --hard?

@ymartin59 sorry, I didn't see your comment. We had different base commits for this branch, that was leading to merge conflicts. Yes I did a hard reset and cherry picked your latest commit adding Perl as spk dependency.

As I have rebased to the current head @ master and done some cleanup is there anything left?

[ymartin59]

In my opinion, good for merge and publish