Tcpdump is a powerful command-line packet analyzer tool used in Unix and Linux operating systems. It allows users to capture and display network packets flowing through a network interface in real-time or saved to a file for later analysis. This tutorial covers the basic tcpdump filters like source ip, host, interface, specific port, udp port, …
Linux
The hardware vendor info or serial number can be very helpful to open a support case for Linux admins. We will cover this topic today to get this info from Linux system. We will use dmidecode command to get this info. The following examples show us three different platforms, physical servers, VMware VM and Openstack …
No space left on device usually means that we run out of disk space. But in rare cases, we still have some space when we get this error. People will get confused when they get this error. Here is the troubleshooting process about this. “No space left on device” even though there is space # …
Rsync is a unique, full-featured file transfer facility. It can perform differential uploads and downloads (synchronization) of files across the network, transferring only data that has changed. How does Rsync work? Rsync faster than scp or sftp? How to use Rsync to sync files between servers? For example, if there is a local copy of …
Sometimes when we ssh to Linux box, we get this error “WARNING: Your password has expired.” You must change your password now and login again! Changing password for user ocp. Changing password for ocp.” What does “WARNING: Your password has expired.” mean? That means the password for this account expired. We need to change the …
Rp_filter is short for reverse path filtering on Linux. We can use this to filter packets on Linux. Here are 5 common questions about rp_filter. What is reverse path filtering? Reverse path filtering is a mechanism adopted by the Linux kernel, as well as most of the networking devices out there to check whether a …
NFS performance is important for the production environment. In this tutorial, we will review how to use DD command to test local storage and NFS storage performance. Test nfs storage performance on Linux There are some differences between each testing command. We choose dd command in the following example. dd – without conv=fsync or oflag=direct. …
A system is having a single core, and if there is a single process consuming all the CPU Time, then CPU utilization will show 100% utilization. But in case of multi core systems it is not necessary that all the CPU’s are been used for running all processes. In such cases uneven CPU utilization across …
Linux monitoring is not an easy task for Linux admins. Luckily we have open-source software to monitor these metrics now. Today we are going to learn Linux metrics we can monitor using this monitor bundle Telegraf/Influxdb/Grafana. We can monitor the following metrics with TIG system. Monitor Basic OS metrics For Linux system Monitor Application Metrics …
Troubleshooting a slow network issue on Linux is not an easy task. We are going to dive into this issue with network metrics. Setting up a monitor on each network metric can help us speed up the troubleshooting process. Hope this post can give you more ideas on how to fix a slow network issue …