Arm / Nyx questions

Question

I am on Linux Debian Stretch (9, testing). Running the following Tor version:

Tor version 0.2.9.10 (git-e28303bcf90b842d).

I recently installed Tor on one of my servers and configured as a non-exit relay as follows:

ORPort 9001
DirPort 9030
SOCKSPort 0
RunAsDaemon 0
Address myIP
Nickname myNick
ContactInfo myContact
ExitPolicy reject *:*
ExitPolicy reject6 *:*

Questions:

1. Why should I run arm monitoring tool using this command:

   sudo -u debian-tor arm
   

   I have already defined alias, so it's no problem, but I am curious as to why I can't just use:

   sudo arm
   

   I tried it and it seems to work the same.

2. Should I do anything regarding the following arm notices:

   05:34:45 [ARM_NOTICE] Unable to prepopulate bandwidth information (insufficient uptime)
   05:34:45 [ARM_NOTICE] Tor is preventing system utilities like netstat and lsof from working. This means that arm can't provide you with connection information. You can change this by adding 'DisableDebuggerAttachment 0' to your torrc and restarting tor. For more information see... https://trac.torproject.org/3313
   05:34:45 [ARM_NOTICE] No armrc loaded, using defaults. You can customize arm by placing a configuration file at '/var/lib/tor/.arm/armrc' (see the armrc.sample for its options).
   

   I mean the first notice is pretty clear, but the next two not so much.

3. I have noticed here that the tag arm is now called nyx, so: Should I uninstall tor-arm package and install some nyx package? I can't find any.

Answer 1

Why should I run arm monitoring tool using this command:

sudo -u debian-tor arm

Running any process as root should generally be avoided. If anyone compromises the process, she'll have full root access. In case of Tor, Tor itself is running as debian-tor. If you your Tor processes is compromised the next logical step is to try to evaluate privileges. One thing an adversary might try is to compromise arm. If this succeeds, the adversary gains full root access if arm is running as root but only little more permissions if it is running as debian-tor.

Tor is preventing system utilities like netstat and lsof from working. …

This is a security measure, if your system is compromised, it makes it harder for an adversary to obtain keys and connections from an existing Tor process.

No armrc loaded, using defaults …

You can customize arm using the options that can be found in armrc.sample. You can look at the sample using zless /usr/share/doc/tor-arm/armrc.sample.gz.

I have noticed here that the tag arm is now called nyx, so: Should I uninstall tor-arm package and install some nyx package? I can't find any.

I assume that Nyx will be shipped at some point. Until then you arm should work just fine.