Technology Insights

Find Out What Applications Are Installed From An RPM Package On Linux

Earlier today I was upgrading some packages on a CentOS Linux server and was curious what applications were actually installed with the coreutils RPM package. I knew that this was one of the main RPM packages that had a ton of various applications installed with it however I was not sure specifically which ones. Below are some examples of how to use RPM to find out exactly what is installed with a specific RPM package.

Technology Insights

Dell OMSA Repo Install Error On CentOS: Command line error: no such option: –disableplugin

I wrote another article recently about an issue when attempting to install the srvadmin-all RPM package provided by the Dell OMSA repository. It is likely that when you are installing the OMSA repository that you will receive an error on CentOS and possibly on other versions of Linux. The yum OMSA repository is installed via a file available from Dell called bootstrap.cgi. Below I describe the issue when installing the OMSA repository and provide a couple methods to resolve the problem.

Technology Insights

Error(s) executing /usr/bin/nagios -v /usr/share/nagios/monarch/workspace/ nagios.cfg Permission Denied

Earlier in the week when moving Nagios from one server to another I ran into a bunch of random issues with Monarch which is the Nagios configuration file manager I use. After I got everything installed and thought that I was past any errors I ran a Pre Flight Test on the Nagios configuration files which returned an error. In the article below I describe in more detail the error that displayed, how I went about troubleshooting the error, and what I finally did to resolve the error.

Technology Insights

Daemon In Linux To Open A TCP Port That Listens On Every IP And Logs TCP Connections

Yesterday a colleague at my company was doing some testing with a potential partner and they needed to open a TCP port on one of our development servers so an application could bind to that port. At first I wasn’t sure how I should do this since the port didn’t need to do anything but listen for incoming connections and the remote application would simply connect to that port. To get something up immediately for them I simply had our web server listen on the requested port which worked however I did not want the web server running on this port for long so I needed to come up with another solution to simply open the port, listen for connections, and possibly log those connections so we could troubleshoot if necessary. I ended up finding an application called tcpsnoop which I explain how to compile and use below.