Hacker News Reader

Comment by mrweasel | Hacker News Reader

I love the multiplexing feature. We have a client who require password, ssh key and MFA. All services are behind a bastion host, which only accepts trafic from select IPs. SSH multiplexing and proxy configuration allows me to enter the password and TOTP just once instead of every time I need to access a service behind the bastion host.

View on HN

Of course if the multiplex stalls or goes down so do all of the connections you have running through it. It's like screwing up Gnome Terminal or similar that uses a main server and multiple clients. Screw one pooch and you're whole session of things is similarly screwed.

Another annoying "feature" is that opening a new shell with ssh -X will not enable the forwarding if the original master connection was not enabled with it.

True, but I never see SSH go down, unless there's a network issue, in which case I lose all my connections anyway.

Indeed; however, if you have a lingering control file (because an old ssh process was killed, or there was a power failure and it was somehow not removed), it will either refuse to use it, or (occasionally, and I haven't been able to pinpoint when), would just wait there forever.

edit: a typo

Sounds more like a bug than a disadvantage

I have these shell aliases configured, to check and delete the master connections. (Often I end up with stale connections when I have a VPN up, and then just sleep my laptop.)

alias ssh-MasterConnection-check="ssh -O check " alias ssh-MasterConnection-exit="ssh -O exit "

+ then you use them as 'ssh-MasterConnection-check host' etc.

Is there much of an upside to doing the multiplexing on the client side instead of on the server (with something like tmux)?

It seems to me like the session persistence tmux gives would be worthwhile if you have a lot of simultaneous sessions going.

scp and sftp will multiplex too. Remote tab-completion for file transfers also becomes much more approachable this way.

scp remote:~/err[tab] .[enter]

Also, bastion connections get multiplexed as well so connecting to multiple different hosts behind the bastion goes faster.

So you’re saying SCP will tab complete through the control master socket? Neat.

I never saw the value of tmux unless your running a command that can’t be interrupted.

Having multiple windows vs tabs on my desktop seems so much easier.

Yes, I agree. What is the usage for tmux? Multiple tabs on a quake-style dropdown terminal on a desktop (like guake) does seem much easier than tmux, especially when gnu-screen is always available when you need to run an uninteruptible command.

From what I gather, tmux is useful if you are basically running a persistent remote workspace via terminal on a server and treat your desktop like a thin-client, is that correct?

for me this is a common pattern:

  ssh x

then in other windows, I do things like this:

  scp file x:
  ssh x command
  rsync from/ x:to/
  emacs /ssh:x:filename    (this is tramp mode)

edit: one more thing

  ssh x -o BatchMode=yes command

if you have an automatic script to run on a remote machine, adding BatchMode=yes will make it error out instead of stopping and asking for a password

Reply on news.ycombinator.com