Compiling libhid for Raspbian Linux on a Raspberry Pi

My son and I are working on a project using a Raspberry Pi and I needed to be able to talk to a USB HID device. This requires a software library called libhid but unfortunately it is not available as a package on Raspbian linux. I downloaded the source and attempted to compile it but ran into an error:

lshid.c:32:87: error: parameter ‘len’ set but not used [-Werror=unused-but-set-parameter]
cc1: all warnings being treated as errors
make[2]: *** [lshid.o] Error 1
make[2]: Leaving directory `/root/libhid-0.2.16/test'
make[1]: *** [all-recursive] Error 1
make[1]: Leaving directory `/root/libhid-0.2.16'
make: *** [all] Error 2

After some googling I found a couple others on the Raspberry Pi forums that ran into the same problem. One of the commenters came up with a simple fix that requires a quick edit of the source code. In ~/libhid-0.2.16/test you need to edit the file lshid.c

Here is the code before making the edit:

39 /* only here to prevent the unused warning */
40 /* TODO remove */
41 len = *((unsigned long*)custom);
42
43 /* Obtain the device's full path */


Here is the code after the edit.
You need to comment out line 41 and then add len = len; and custom = custom;

39 /* only here to prevent the unused warning */
40 /* TODO remove */
41 //len = *((unsigned long*)custom);
42 len = len;
43 custom = custom;
44
45 /* Obtain the device's full path */

After editing the file simply run configure, make and make install like normal. The library will be put into /usr/local. Make sure you run sudo ldconfig before trying to compile any software that uses libhid. Thanks Raspberry Pi forums!

Bandwidth limits for guest wifi on an ASA 5505

At work we have free wifi for our customers as a nicety and so they can download our smartphone app if needed. Initially I set it up with no bandwidth limits with the idea of keeping an eye on it and locking it down if there was abuse. Over the past few weeks my MRTG graphs showed several spikes where the free wifi hit 10mbps. That is a big chunk of our internet connection so I decided it was time to limit the bandwidth. Since I'm not a Cisco expert it took some Googling to find the best way to do this. I found a couple resources that helped me put together what I needed. The free wifi network is on a separate VLAN with it's own IP subnet.

Here is interface definition for the VLAN

interface Vlan92
  nameif freewifi
  security-level 50
  ip address 192.168.92.1 255.255.255.0


Here is the syntax I used to limit the freewifi VLAN to 2mbps. The limit is applied to the subnet used by the freewifi VLAN.

access-list ip-qos extended permit ip 192.168.92.0 255.255.255.0 any

access-list ip-qos extended permit ip any 192.168.92.0 255.255.255.0

class-map qos

  description qos policy

  match access-list ip-qos

policy-map qos

  class qos

    police output 2000000 2000000

    police input 2000000 2000000

service-policy qos interface freewifi

Testing

My initial thought for testing the bandwidth limits was to connect to the freewifi VLAN and simply use one of the internet speed testing web sites. The speed test web sites worked fine for download speeds but the upload tests kept reporting that they were getting the full bandwidth of the connection. It seemed like the upload limit wasn't being enforced. I tried all of the popular speed testing sites and got the same result. Downloads were limited to 2mbps and uploads were running at the full speed of the connection. Hmmm...

I reviewed my settings on the ASA and everything seemed like it was correct. I decided to do a different type of test to see if I would get a different result. I created a 10MB file and then tested uploading and downloading it to and from a server out on the internet using scp. This test gave me the results I was expecting. Both upload and download of this test file took about 35 seconds which is inline for a 2mbps connection. I then tested transferring the same file on the inside VLAN which has no bandwidth limits and the scp transfer time was 4 seconds. I'm not sure what was going on with the speed test sites but the upload speeds were not reporting accurately for me.


Monitoring status

You can watch the bandwidth limits in action using the 'show service-policy police' command. If the limit is exceeded the output will show the number of packets and bytes that have exceeded the bandwidth limit.

This is the command output before sending any traffic:

asa5505# show service-policy police

Interface freewifi:
  Service-policy: qos
    Class-map: qos
      Output police Interface freewifi:
        cir 2000000 bps, bc 2000000 bytes
        conformed 1306 packets, 907993 bytes; actions:  transmit
        exceeded 0 packets, 0 bytes; actions:  drop
        conformed 0 bps, exceed 0 bps
      Input police Interface freewifi:
        cir 2000000 bps, bc 2000000 bytes
        conformed 1072 packets, 192021 bytes; actions:  transmit
        exceeded 0 packets, 0 bytes; actions:  drop
        conformed 0 bps, exceed 0 bps


This is the output after transmitting several test files:

asa5505# show service-policy police

Interface freewifi:
  Service-policy: qos
    Class-map: qos
      Output police Interface freewifi:
        cir 2000000 bps, bc 2000000 bytes
        conformed 149813 packets, 127878453 bytes; actions:  transmit
        exceeded 10273 packets, 14716462 bytes; actions:  drop
        conformed 3384 bps, exceed 360 bps
      Input police Interface freewifi:
        cir 2000000 bps, bc 2000000 bytes
        conformed 157493 packets, 123699017 bytes; actions:  transmit
        exceeded 15083 packets, 21214456 bytes; actions:  drop
        conformed 4928 bps, exceed 760 bps





Resources

Source: http://community.spiceworks.com/topic/137645-bandwidth-limit-vlan-on-asa-5505

Source: http://www.youtube.com/watch?v=Xb2A3Xekp7Q

Template Nagios check for a JSON web service

I wrote two different custom Nagios checks for work last week and realized I could make a useful template out of them. After writing the first check I was able to reuse most of the code for the second check. The only changes I had to make had to do with the data returned. So I decided to make this into a generic template that I can reuse in the future. The check first verifies that the web service is responding correctly and then checks various data returned in JSON format.  While writing this template I found this really cool service (www.jsontest.com) that let me code against a service available to anyone who wants to try out this Nagios check before customizing it. This is the first time I have used Python's argparse function and I have to say it is fantastic. It makes adding command line arguments very easy and the result is professional looking.

My github repo can be found here: https://github.com/matt448/nagios-checks

Here is the code in a gist:

Nagios file paths on Ubuntu and simple backup script

This is more of a note to myself than anything else but might be helpful to others. Here are the config and data directories for Nagios when installed using packages on Ubuntu 12.04.


Config files
----------------------
/etc/nagios3/
/etc/nagios3/conf.d
/etc/nagios-plugins/config
/etc/nagios

Plugin executables
---------------------
/usr/lib/nagios/plugins

Graphing (pnp4naigos)
----------------------
/usr/share/pnp4nagios/html
/var/lib/pnp4nagios/perfdata

Other
-----------------------
/var/lib/nagios
/var/lib/nagios3



Here is a very simple backup script for Nagios on Ubuntu 12.04