On 6/16/2017 8:56 AM, DuaneVT . wrote:

Good to know about RC1. I had months ago disabled access to root via ssh. Even I have to ssh in as SU with a password. I was wondering if this exploit hack was seen by others, just a heads-up.

Duane KA1LM

ANY port that you have open to the outside world is going to add to the risk you enjoy (!) from being connected to the network.  There are well-known ports; in the U/Lin-UX world, the goldmine ports (ie those which are reserved to the root group, are those port #s < 1024...and once you have root, all bets are off as to what you can do.

That many people have their routers set up to automagically establish persistent connections when any outbound traffic port is opened, this means that if your machine is pwned and a rogue daemon sets up a channel to a command and control system, YOUR machine is part of a botnet...doing who knows what.

In 7 years of running an asterisk box, I have NEVER had a reason, while away from the site, of having to log in to do something.  Now, it may be different if your box is on a mountain top and inaccessible for 4 months of the year...but, my rule is, if you can drive there, then I don't enable shell access from the outside.  I turn off, on my router, PnP.  I deny ANY to ANY inbound connections as the default ACL.  My boxes have static IPs on the inside of a NAT, and ports are routed to specific host/ports.  Fail2ban is running, and, as a luxury, my logs are NOT stored on the machines that ARE accessible; the first thing that a miscreant is going to do is try and erase system log entries of what they've done. 

So...how to do those things that you have to do administratively?  Think belt and suspenders. 

One of the nice things about asterisk is that you can script almost anything both inside the application as well as the operating system to respond to DTMF.  Now, I realize that not everyone has this ability, but, being all my boxes are accessible via the net in some manner...I have a receive-only node on an oddball frequency in a second location locally, which also has an echolink node assigned...and have scripted the admin functions *I* use on a regular basis.  Things like reboot the box...restart asterisk...even down to connect and disconnect nodes (ie command *node#3 or *node#1 to connect or disconnect node#), etc.

Add in the fact that you can have control over the GPIO pins on the DMK and RIM URIs, and you can even do relay-driven (I like electromechanical stuff) things: turn on fans, turn off fans, turn on power, turn off power...the possibilities are endless, if you think through just what it is that you need to when you supposedly have to log in via a shell.  Haven't quite worked out how to mount a cdrom that has a clonezilla image of a fresh box to restore a system from a DTMF command...but, I'm sure with some hacking, even that could be done to remotely restore a system that HAS been trashed. 

In my opinion, we have to get away from thinking that we need to have terminal access to what is (or should be) essentially an appliance that controls radios.  And, no, I'm not thinking that a web interface is necessarily the way to go either. 

 

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