Ubuntu: Using strace to get a view into file and network activity of a process

strace is a handy utility for tracing system, file, and network calls on a Linux system.  It can produce trace output for either an already running process, or it can create a new process.

Some of the most common troubleshooting scenarios are needing to isolate either the network or file system activity of a process.  For example to determine whether an application was attempting to reaching out to a server on the expected port, or to understand why a startup configuration file was not being read from the expected directory.

Continue reading “Ubuntu: Using strace to get a view into file and network activity of a process”

Ubuntu: Using Fiddler to analyze Chrome/Firefox network capture

ubuntuThe prevalence of the long chains of firewall and reverse proxy solutions present in production infrastructure (and made even more popular with the dynamic routing introduced with containers) has made analysis of the end-user side of the network exchange a critical tool in troubleshooting.

Fiddler has long been a solid tool for both proxy capture as well as analysis of the end user application traffic on the Windows platform.  However, troubleshooting issues with customers always required them to first install the tool on their desktop, and at times corporate policies would prevent installation.

Now, with the built-in capabilities of the Chrome DevTools and Firefox Network Monitor, the capture can happen directly from the end user’s browser without any external tool installation.  If that session needs to be analyzed by higher level support resources, it can be exported as an HTTP Archive (HAR), and then imported into Fiddler for analysis at a later time.

And since the release of Fiddler for Linux, the analysis of the HAR can be done directly on the Ubuntu desktop.

Continue reading “Ubuntu: Using Fiddler to analyze Chrome/Firefox network capture”

Ubuntu: Pre-Validate Network ACL and Firewall Connectivity with Netcat

ubuntuAlthough virtualization has pushed a self-service culture for infrastructure, it is still common in production environments to need your  Network Operations team to open the required ports necessary for any new application deployment.

So, while you may be able to create the base virtualized host, you can’t go much further without the network connectivity.  And there is nothing worse than finding out half way through your full stack deployment that the reason you keep hitting errors is because a stray port was not opened.

I would suggest pre-validating all the TCP and UDP ports you expect open.  This can be done pretty simply by using netcat on both sides of the communication.

Continue reading “Ubuntu: Pre-Validate Network ACL and Firewall Connectivity with Netcat”

Ubuntu: Hang While Installing gutenprint as Network Driver

If you experience hanging when installing the gutenprint drivers for a network printer from the desktop, try manually installing the gutenprint drivers from the console first.

Most likely, you will see a screen like below, and the progress bar will continually cycle but never end.

gutenprint-searching2

If you can’t cancel, you can use the ‘xkill’ command from the console and click on the dialog window.  But you will also need to kill the process, and that can be done by  finding the process id using:

Continue reading “Ubuntu: Hang While Installing gutenprint as Network Driver”