norobo

norobo

Norobo is a spam phone call blocker for land lines. It uses a modem (remember those old things?) connected to a PC, RPi, etc. and plugged into any phone jack in your house.

Motivation

Spam / robo calling is an epidemic and relativly little has been done to stop it. There are some great services available like Nomorobo but unfortunately not all carriers offer the simulring feature it requires. There are also features I want that that type of service may not offer. E.g., temporarily block a number if it calls more than once in a minute, simultaneously check multiple online blacklist services, web interface for the call log, etc.

How it works

When a call comes in, your phone rings once, norobod gets the caller ID from the modem, runs the caller's info through the filters, and hangs up if the filters flag it as spam. You feel immediate pleasure from hearing the single ring, knowing norobod just hung up on a sleezy spammer.

Compatibility

It has been tested on Linux using a Zoom 3095 USB Mini External Modem. It can be run on an RPi or other small ARM based computers capable of running Linux & Go apps. It should also (in theory) work with any Hayes compatible modem that supports caller ID. It may also work on Windows and OS X.

Install

Currently, it must be built from source. You'll need the Go tools, if you don't already have them installed. Then clone this repo and build the code in cmd/norobod.

How call filters work

norobod currently supports three filters: local, exec, Twilio.

Local

Local filters run locally and do not send incoming call info out to external services to perform filtering. There are two types of local filters: allow and block. Both are optional. Allow filters are special in that they run first and not concurrently with any other filters. If a call matches an allow filter, it is allowed through immediately with no further filtering. Block filters run concurrently with the Twilio filter, if configured. If a call matches a block filter, norobod will answer the call, immediately hangup, and cancel any other concurrent filters that are running.

Twilio

The Twilio filter is optional and requires a Twilio account. Creating an account is easy and only takes a few minutes. There is a charge for each lookup but it is minimal ($0.005 per lookup at the time of this writing). Once you've set up an account, go to the Lookup Add-ons page, select the Whitepages Pro Phone Reputation add-on, and install it (Note: it installs on your Twilio account, not your local PC).

Exec

The exec filter allows users to create their own filters(addon) to run when a call comes in. Configuration notes are down below.

Filter Configuration

Local

Local allow and block filters are configured using a simple CSV format. The fields are (in order): description, name, number, function. All fields are strings. The name and number fields are regular expressions. The function field must be either an empty string or one of the built in filter functions:

• NameContainsNumber matches any call where the caller's name contains the caller's number. All symbols are stripped from both before the comparison is made.
• NumberContainsName is the opposite of the previous rule. It matches any call where the caller's number contains the caller's name. All symbols are stripped from both before the comparison is made. See filter/block.csv for examples.

The same format is used for allow and block filter files. Create a file for one or both as desired. Use the -allow and -block command line options to enable them. E.g.,

norobod -allow path/to/allow.csv -block path/to/block.csv <other options>

Exec Commands

Allows users to execute external commands as a filter. Users can create an executable add-on that sends either block or allow to std.out to block or allow a call.

To use this feature define the command to run with -exec and the command args with -exec-args. Exec-args uses the Go text/template format. E.g. "-n {{.Number}}"

./norobod -exec testFilter -exec-args "-n {{.Number}} -name {{.Name}} -t {{.Time}}"

Twilio

There are no configuration files for the Twilio filter. To enable it, run norobod with the -twlo-sid and -twlo-token command line arguments. E.g.,

norobod <other options> -twlo-sid <your Twilio SID> -twlo-token <your Twilio token>

Your Twilio Account SID and Auth Token can be found by logging into your Twilio account and looking on the home tab.

Running

On Linux:

• Plug the modem in to the PC
• ls /dev to find the modem's name. It's /dev/ttyACM0 for me.
• ./norobod -c "/dev/ttyACM0,19200,n,8,1"

If it exits immediately with permission denied, you probably need to add yourself to the dialout group. Check who owns the modem and what group it belongs to first:

$ ls -l /dev/ttyACM0
crw-rw---- 1 root dialout 166, 0 Dec 30 21:52 /dev/ttyACM0

Then confirm our suspicion that your user is not in the modem's group:

$ groups dgnorton
dgnorton : dgnorton adm cdrom sudo

Then add yourself to the dialout group:

$ usermod -a -G dialout dgnorton

Running as a daemon

There is an example init script in etc/norobo that may work for you if you're running Linux.

• Copy etc/norobo from the source to /etc/init.d/
• Open the init script in a text editor and make sure the cmd= line is starting norobod with the command line options you want
• sudo chmod +x /etc/init.d/norobo
• sudo update-rc.d norobo defaults
• sudo service norobo start
• To make sure it's running, tail /var/log/norobo.log

Call log

Use the -call-log path/to/call_log.csv command line option to specify a call log file. The file is a comma separated value format. The fields are (in order): time, caller name, caller number, action taken, filter name, rule description. The call log can also be viewed by web browser on port 7080.

Desktop notifications

If you happen to be running it on a Ubuntu Desktop machine and would like desktop notifications, this shell script one-liner will work.

while inotifywait -e close_write call_log.csv; do notify-send "Call From..." "`tail -n1 call_log.csv | awk -F, '{ print $2 " at " $3 }'`"; done

Dev notes

On Linux / Unix, use socat to create a pair of connected virtual serial ports for development and debug. There's a hacky little modem simulator in cmd/modem. norobod will talk to it and think it's talking to a modem. The modem simulator has a simple HTTP API for simulating inbound calls. The norobo/etc/norobosim.sh bash script can be used to automate the process of starting up socat, modem, and norobod. It starts socat in the background and uses tmux (terminal mux) to display modem & norobod output in separate panes. It also creates a third pane for the dev to run curl commands to post simulated inbound calls to modem. You may need to tweak the norobosim.sh script to suit your environment / needs.

Manually running socat, modem, and norobod...

Create a pair of connected virtual serial ports:

$ socat -d -d pty,raw,echo=0 pty,raw,echo=0
2015/12/30 20:22:20 socat[9498] N PTY is /dev/pts/30
2015/12/30 20:22:20 socat[9498] N PTY is /dev/pts/31

It will tell you the ports it created. In the example above it's /dev/pts/30 and /dev/pts/31. Pass one of those to the connect string when starting the modem simulator and the other in the connect string to norobod.

Simulate a call

curl -X POST http://localhost:8087/call --data "name=John+Doe&number=111-222-3333"