what is usbmuxd process

See > http://www.macinside.info/process.php?name=usbmuxd You shouldn't worry about it

During normal operations, iTunes communicates with the iPhone using something called “usbmux” – this is a system for multiplexing several “connections” over one USB pipe. Conceptually, it provides a TCP-like system – processes on the host machine open up connections to specific, numbered ports on the mobile device. (This resemblance is more than superficial – on the mobile device, usbmuxd actually makes TCP connections to localhost using the port number you give it.)

On the Mac, this is handled by /System/Library/PrivateFrameworks/MobileDevice.framework/Resources/usbmuxd, a daemon that is started by launchd (see /System/Library/LaunchDaemons/ com.apple.usbmuxd.plist). It creates a listening UNIX Domain Socket at /var/run/usbmuxd. usbmuxd then watches for iPhone connections via USB; when it detects an iPhone running in normal user mode (as opposed to recovery mode), it will connect to it and then start relaying requests that it receives via /var/run/usbmuxd – this is to say, usbmuxd is the only thing that actually speaks USB to the iPhone. This means that third-party applications which wish to talk to the iPhone must either do so through usbmuxd, or usbmuxd must be replaced.

Hi,

Thank you for the explanation. It looks like since I've installed Yosemite there is a bug in usbmuxd that collapses my kernel TCP/IP stack.

Once you connect our iPhone 4 (maybe iPhone 5 does not suffer this problem) to your mac, then you wait for about 1 or 2 days (it may take longer) then I cannot open TCP connections to my own host (I'm doing Java development and I notice this problem because I can no longer open Java in debug mode).

This is what I do to detect this problem:

open terminal

$ ps -ef | grep usbmuxd

this shows the process number, in my case it was 51

$ netstat -av | grep 51 | wc -l

in other words, grep network status using process number as filter, then count the number of lines.

it shows 1311 in my computer at this moment.

you can see the details using other commands...

I'm going to see if this process can be tuned but a fix in 10.10.2 version is required!

Great answer! but just to be sure - Is it wise to only allow usbmuxd daemon outgoing connections on the local network? (as a Rule to Snitch) ? will this be safer than allowing it any connection whatsoever - which can then be maliciously used by some remote host?

Whether this daemon is safe is up to you to decide. If this is really usbmuxd, then it is normally considered safe. If it's not really usbmuxd you're looking at here, or if the nefarious hackers have cracked your security or infiltrated your system with advanced persistent malware, or the advanced 0day attack launched by elite regional security services have replaced or subverted usbmuxd, then not so much. Or you can remove LittleSnitch and get on with whatever you were doing. Your call.

😝

Thanks for this! I knew sort of what usbmuxd does, but your fuller explanation is much appreciated, kgravity!