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Mosh: the mobile shell

mosh.mit.edu

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Re: Mosh: the mobile shell

#101

Post by spdustin »

chitta wrote: post #89
spdustin wrote: post #25

Earlier quoted context omitted.

I'll chime in and say: Support for IPv6. It's ... self evident? I think we've reached a point that it's okay to call out a network client that doesn't support it.

I am not sure I understand. How is it self-evident? Is there a benefit over using mosh over IPv4? Performance, stability,anything else? Does it add anything to what mosh can do over IPv4. Is the benefit from the client end or the server end or in-between.

Connecting to servers that aren't given an IPv4 address (because NAT sucks)?

Re: Mosh: the mobile shell

#102

Post by gue5t »

teejmya wrote: post #50
aerovistae wrote: post #38

I'm not a security researcher, but somehow I suspect the "maintaining connection while switching networks" holds potential for a flaw.

If my client session dies (laptop kernel panics or runs out of battery) then mosh will notify me on the next login that "there are sessions running with these PIDs" I've tried to reattach sessions to no avail, mosh was designed this way. I have to just kill the sessions. Looks like I'm not alone in this either: https://github.com/mobile-shell/mosh/issues/394

There's no way to know if a machine you can't contact is on the other side of a network partition or if it has died/disconnected/given up. You could have the client try to persist its state across local reboots, at least to the extent necessary to kill the session (in case the latest crypto state needed to resume couldn't be saved before the system died), in which case you would have to kill fewer sessions.

Re: Mosh: the mobile shell

#104

Post by icebraining »

esac wrote: post #42
tombert wrote: post #40

Mosh is great, but I kind of stopped using it once I discovered Tmux so I could resume a session if the connection dropped. It's not that Mosh does anything wrong , but SSH has more features, and is supported by basically everything ever. Consequently, I stick with old-school SSH.

well, i've been using mosh for two(?) years and it's not perfect. >lost sessions cannot always be resumed, not even root can force that. >you can't scroll the terminal unless you use screen inside mosh >can't use mosh from the university network because UDP ports are filtered >can't autocomplete hosts in the config (ssh can do that) but i still use it and would miss it very much, the whole experience is much smoother…

can't autocomplete hosts in the config (ssh can do that)

If you mean writing "ssh " and having it auto-complete, that's a feature of the shell (usually with some "plugin" to add support for that particular command). They added support for Bash in 2012 [1], what OS and shell are you using?

[1] https://github.com/mobile-shell/mosh/issues/248

Re: Mosh: the mobile shell

#106

Post by neves »

andy_ppp wrote: post #83
neves wrote: post #72

Earlier quoted context omitted.

Hey, never, but never, go out of an elevator that isn't leveled in the floor. By the description, I understand that he jumped from the elevator. If the elevator started to move, he could have been cut in half. This happened other day in my city. If you are stuck in a elevator, wait for professional help to take you out.

I once dreamt I was cut in half by a lift. It was not at all fun, so I'd definitely follow this advice :-D The other piece of lift related advice (that I really enjoy saying in more crowded, rickety lifts): I once read if in a lift that is falling you should attempt to lie flat on the bottom of the lift to limit the impact - preferably on top of another human. Some hacker news physicist will prove me apocryphal here…

I've read somewhere that a free falling elevator is almost impossible due to its automatic brakes.

Re: Mosh: the mobile shell

#107

Post by Karunamon »

ukd1 wrote: post #48

mosh + zerotier = win for random home servers, imho

For anyone else that was curious, zerotier appears to be a virtual network tool, kind of like Hamachi but not run by a terrible company and with a much saner pricing scale.

Re: Mosh: the mobile shell

#108

Post by justizin »

zobzu wrote: post #85
somebehemoth wrote: post #79

Earlier quoted context omitted.

I think caution is good, but I am not sure "Don't use it" is a fair assessment for all use cases given Mosh's technology and track record over the years. Of course SSH is more battle tested but, Mosh has a FAQ entry just for this concern: "In one concrete respect, the Mosh protocol is more secure than SSH's: SSH relies on unauthenticated TCP to carry the contents of the secure stream. That means that an attacker can…

Mosh requires OpenSSH to run so no matter what, using Mosh is ALWAYS less safe than OpenSSH alone since all it does is add functionality on top. Now, I wrote a 3DES-telnet tool back in 1996 and it has zero security vulnerability. That's 20 years. Safe as hell! Yeah exactly. Everyone uses OpenSSH. Very few use Mosh. Invalid comparison.

> Mosh requires OpenSSH to run so no matter what, using Mosh is ALWAYS less safe than OpenSSH alone since all it does is add functionality on top.

Not sure I'd agree with this, since after initial session establishment, it completely replaces the functionality of OpenSSH in a way that guards against privilege escalation and authenticates every packet.

I do agree that there are some concerns with how 'battle tested' it is, but not sure I believe this about "audits" since, I mean, the entire world was using OpenSSL to build the entire internet for ages and we just found out it was one guy scraping through the bug tracker for far too long.

The model of mosh is more secure than SSH, though its' session resumption could potentially expose a hole if someone has your token and session keys, they can resume your session.

Re: Mosh: the mobile shell

#110

Post by OJFord »

neves wrote: post #72
mholt wrote: post #24

> Mosh (and its tolerance for high packet loss) helps Iain Learmonth escape from an elevator. Um, wow! https://mosh.mit.edu/elevator.txt

Hey, never, but never, go out of an elevator that isn't leveled in the floor. By the description, I understand that he jumped from the elevator. If the elevator started to move, he could have been cut in half. This happened other day in my city. If you are stuck in a elevator, wait for professional help to take you out.

But if it's stopped, why would you expect it to be more likely to move suddenly (and without the doors closing) because it's not level?

I've often seen (and used) lifts with notices up like:

    Warning: does not level. Wheelchair users use other lift.
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