Entries Tagged as 'Linux'

No webcam Image on USB webcam for Ubuntu 14.04

I have been doing google hangouts more for work, and most folks who use Google hangouts also have a webcam setup so you can see the person you're speaking with. This is useful because as most communicators know, so much communication is non-verbal. It's helpful to have an image of the person you're talking to.

webcamI have just recently changed out my PC case and motherboard for an older server board. The server board, while being slower on the MGhz and RAM speeds, had a lot more CPU cores and RAM amount. On my previous PC, running an older version of Ubuntu (13.04), my USB webcam worked flawlessly. However, on this "newer" PC, my webcam no longer works. First my USB camera didn't even register. I had to unplug it and replug it in for it to register at all. IE: nothing was showing up when I entered the following:

ls /dev/video*

As soon as I unplugged and replugged in the USB video camera, I would get a device here, but when I started up "cheese" (a cam viewer for Linux), I got nothing but a black screen. What was going on?

Looking up some articles on debugging Ubuntu camera issues, I happened on an article that mentioned I try a camera app called "guvcview". I did, and when I ran it, I got the following error message over and over:

Could not grab image (select timeout): Resource temporarily unavailable

Mkay... why can't you grab an image if you see that I have a camera now?

Turns out, the bottom of the article that I found earlier had the answer:

"Some newer webcams produce high resolution images at 30fps. This is a lot of data. If your USB cable path is too long or convoluted, frames can drop causing flicker or no picture. If you find MJPG format mode produces less flicker than YUYV format mode, then this could be the case. Try plugging the webcam directly into the computer. Then try progressively reconnecting your extension cables or hubs to see how the picture changes. Check you don't have a low speed hub.

You may also see:

Could not grab image (select timeout): Resource temporarily unavailable

This could indicate the frame data not arriving down the long cable fast enough. Check also for cable kinks and tight loops, which like ethernet, cause delayed packets."

BINGO! Apparently my older server board only had the earliest USB ports, which means they are really, really slow. I tweaked with the settings on the "Video" tab in guvcview and was able to get a picture of some kind by dramatically lowering the resolution and camera output type. Unfortunately the camera is still barely usable. Couple that with the relatively low Ghz value of the CPU and slow RAM, I'm not so sure this old server board is worth being a desktop.

Fixing "JRun too busy or out of memory" for PCI compliance

One of our servers here at Vivio is routinely scanned for PCI compliance purposes. Until just recently, we've been using FuseGuard (A Web Application Firewal, or "WAF"), to block intrusion attempts to our web application. With new PCI standards that force us to allow PCI scans through our WAF (or IDS or whatever), we had to allow these requests through, but that brought to light another, different, problem.

During the PCI scan, our Apache logs would get a lot of the following error messages:

[notice] jrApache[13857: 62679]  returning error page for JRun too busy or out of memory

Initially we thought that since the message was coming from the JRun connector, that the issue had something to do with the connector. However, after quite a bit more research, we found it had to do with JRun itself, and the specific number of post parameters it's configured to accept. Any more then the default "100" post parameters, and you'll get the error you see above.

To change the number of post parameters, you will need to update your neo-runtime.xml file. For our case, ours was found here:

NEO XML Example

IMPORTANT: Editing this file isn't particularly easy. Opening it in VIM gives you a big wall of text.

By increasing the following parameter from 100 to 300, we were able to succesfully complete our PCI scan:

<var name='postParametersLimit'><number>300.0</number></var>

Hopefully this helps anyone else having this issue.

Railo CGI remote_addr/remote_host says

When installed on to a Linux/Apache machine, the Railo installers will install mod_proxy_http as the default connector for Apache to Tomcat/Railo. The result is the same as you'd get with any other proxy, where the remote host is replaced with the address of the proxy (in this case and the original requester's IP address is placed in the "X-Forward-For" header.

simplicityIf you need to find the original requestors IP address you can accomplish this in one of two easy ways.

Pull the IP from the X-Forward-For Header
This can be done easily using the following single line of code:


Use the Tomcat Remote IP Valve
This can be done simply by opening up your Tomcat server.xml file and adding a single line of code right under your "<Engine>" tag:

Change this:

<Engine name="Catalina" defaultHost="">

To this:

<Engine name="Catalina" defaultHost="">
<Valve className="org.apache.catalina.valves.RemoteIpValve" />

Restart Tomcat and you'll now see the IP address of the original requesting client populate your CGI scopes.

Apache 2.4 - 403 Forbidden (AH01630: client denied by server configuration)

I recently updated one of my development machines to Ubuntu 13.10 which now uses Apache 2.4 by default. In my case, I had updated a machine that was previously running Ubuntu version 13.04 and had been running Apache 2.2.

Apache 2.4After the upgrade, I was disturbed to find that none of my sites worked! I kept getting Apache 403 (Forbidden) error messages. I figured the upgrade had changed my configurations or something... but after fruitlessly messing with the config files (and seeing nothing wrong with them) I figured I'd look in the apache error log, which is located in /var/log/apache2/error.log by default on Ubuntu 13.10. To my surprise, I found lots of the following errors:

AH01630: client denied by server configuration: /path/to/my/sites

I had never seen that before. Then I noticed at the top of the log file "AH00163: Apache/2.4.6 (Ubuntu)". Ohhhhh....  So we're using the new 2.4 eh? After some google searches, I found out that Apache 2.4 comes with some security enhancements that attempt to make it more difficult for hackers to hide their files on a compromised system. That's neat, but I need to get my sites to work.

After reading a bit of the 2.4 Access Control Documentation, I found that a quick easy fix is to add a directory rule to your main apache config file (/etc/apache2/apache2.conf by default on Ubuntu):

<Directory /path/to/my/sites>
        Options Indexes FollowSymLinks
        AllowOverride None
        Require all granted

Restart Apache, and boom, all sites are now loading just fine. The idea behind these rules is to make it so that hackers who, say, use SQL injection to access your PHP site, have a harder time hiding their files in obscure directories on your system, amond other things.

Hope this helps!


Resetting Pulseaudio on Ubuntu 13.04 (new sound card)

Asus Xonar DSI've been having a huge number of issues with both my sound and my video drivers since upgrading to Ubuntu 13.04. The problem is that my hardware is getting older, and the drivers aren't always "up to snuff" with the latest builds. I understand that hardware evolves and in order to remain current with the latest hardware, backwards compatibility isn't always on the top of everyone's priority list. I'm not mad at anyone about this, but it means that I have to take some time to both figure out what's happening and take the time and spend the money to fix it, and that sucks a little. So, to help others out who may be having the same issues I have, I'll talk a little about what I've been doing to keep up to date.

With my sound, after upgrading to Ubuntu 13.04 I had driver issues with both my SB Live and the onboard sound chip that came with my motherboard. Both would crackle and pop during VOIP conversations due to what I could only deduce as a timing issue due to lack of proper drivers.

To fix this, I needed to get a new supported sound card. I reviewed the ALSA web site and found a card that was fully supported by ALSA and I could also work with as far as affordability & quality. I chose the ASUS Xonar DS which used the fully supported AV66 chipset.

Once I received the card, however, things did not go as well as expected. Pulseaudio would not report that I had even installed the card, and still showed the previous card as being installed. I needed to "reset" Pulseaudio so that it would see my new card. To do this, I ran the following commands:

First, I removed ALSA (just in case it was reporting something incorrectly as well) and Pulseaudio and purged their configurations. This gave me a "blank slate".

$ sudo apt-get remove --purge alsa-base pulseaudio indicator-sound

Next, I needed to re-install what I just removed because, yes, I actually want to use my new sound card:

$ sudo apt-get install alsa-base pulseaudio indicator-sound
After that, we just needed to reload ALSA that's running in memory so that the new/changed modules take effect:

$ sudo alsa force-reload

After this, my shiny new card was working perfectly.

Hope this helps someone else out there!

Update for Ubuntu 14.10

I just recently had to reset pulseaudio for Ubuntu 14.10, and my tried and true article here failed me. Performing these actions in Ubuntu 14.10 no longer fully reset pulseaudio. However, after (a lot of) digging, I found the following bug report, as well as a suggestion to remove a user-specific configuration file located in the user's home directory.

$ rm -rf ~/.config/pulse$ sudo reboot

Once you remove the user-speific config directory, logging out and logging back in (or in this case just rebooting) will get you the default configs.

I also had some trouble with my new video card's HDMI interface. For whatever reason Ubuntu would default to using the HDMI interface over my sound card, so I installed the Pulse Audio Volume Control (pavucontrol), and it allowed me to easily set my preference for my sound card via it's GUI interface.

$ sudo apt-get install pavucontrol$ pavucontrol

After making these adjustments my system was pretty happy. Hope this helps you too!

Update for Ubuntu 16.04 (quiet sound)

Just a quick update for a little change I had to make for this sound card on Ubuntu 16.04. When I did the re-install, I thankfully didn't have to do a reset like I did previously, but the sound was super-quiet, and messing with the GUI tools didn't seem to help much. What FINALLY made the significant change was updating ALSAMIXER via the command-line. Oh, command-line, how I love you so.

Basically, I just typed in the following:

$ alsamixer

Then I just used the arrow keys to modify the levels for my sound card. I set mine to 90, as I prefer to use the physical controls on the speakers directly most of the time.