Mosh-server issue after Mac update to Sequoia

[juanpark]

After updating to iOS 18 on my iPad and Sequoia on my Mac, mosh-server no longer seems to be working on the Mac. Mosh from Blink to other linux devices work fine. Mosh-server on Mac is not working with the following error:

dyld[43782]: Library not loaded: /opt/homebrew/opt/protobuf/lib/libprotobuf.27.1.0.dylib
Referenced from: <55EBD7C0-6AE1-3B19-8CAD-A48819258BB5> /opt/homebrew/Cellar/mosh/1.4.0_16/bin/mosh-server
Reason: tried: '/opt/homebrew/opt/protobuf/lib/libprotobuf.27.1.0.dylib' (no such file), '/System/Volumes/Preboot/Cryptexes/OS/opt/homebrew/opt/protobuf/lib/libprotobuf.27.1.0.dylib' (no such file), '/opt/homebrew/opt/protobuf/lib/libprotobuf.27.1.0.dylib' (no such file), '/opt/homebrew/Cellar/protobuf/28.1/lib/libprotobuf.27.1.0.dylib' (no such file), '/System/Volumes/Preboot/Cryptexes/OS/opt/homebrew/Cellar/protobuf/28.1/lib/libprotobuf.27.1.0.dylib' (no such file), '/opt/homebrew/Cellar/protobuf/28.1/lib/libprotobuf.27.1.0.dylib' (no such file)

When trying to reinstall protobuf:

checking whether protoc matches protobuf... no
In file included from conftest.cpp:68:
./conftest.pb.h:9:10: fatal error: 'limits' file not found
9 | #include
| ^~~~~~~~
1 error generated.
configure: error: in `/private/tmp/mosh-20240925-44975-vmkd63/mosh-1.4.0':
configure: error: Could not build output generated by protoc (/opt/homebrew/opt/protobuf/bin/protoc).
Check that protoc matches the installed protobuf headers and libraries.

Anybody having similar issues? Any solutions?

[carloscabanero]

This looks like an issue on Homebrew, so you may want to look there. But, the simple solution with Blink is to install a static mosh we provide with the —install-static flag.

[carloscabanero]

It is looking like an issue with the firewall on the Mac. But I couldn't find any incantation that fixes it. And from my tests, it looks like it is blocking the "outbound" traffic, which is even weirder. Will continue playing with it, but we may need to reach the dev forums then.

[carloscabanero]

We found what the issue is (many thanks to rrgeorge), but don't have an easy solution for it yet. The good news is that on your side, it looks like it should be ZeroTier the one solving it too, and once they do, you should be able to run mosh-server normally: mobile-shell/mosh#1254 (comment)

[juanpark]

That is very good news. Thank you for the effort. I will be patiently waiting for the update.

[fmt]

@carloscabanero Any news on this issue?

[carloscabanero]

Starting from the workaround. As this is an issue with protections over the local network, the easy fix is to connect over a network like Tailscale. Then Tailscale is responsible to request access and all connections made through it will go through.

What we found is that due to the way the Local Network protection works, there always needs to be a parent process hanging that is responsible for the Local Network permission. The main problem with fixing mosh-server on its own is the ssh -> mosh-server flow. SSH doesn't need any special network permissions, but when it disconnects after starting mosh-server, mosh-server will be "orphaned".

We tried a variety of things like trying to have mosh-server request permission on its own, etc... but none of them are trivial. The new macOS doesn't have any new ways to handle this (like manually adding a command to the "firewall" list), and from what I discussed with engineers at WWDC, they were not sure that would be something they wanted to add.

Another workaround is to start mosh as an agent somehow. We are considering something like this for a Blink version on the Mac. But this is all on paper at the moment.