The cat command in Linux is a versatile and widely used utility that stands for “concatenate.” Its primary function is to read and display the content of one or more files and, if desired, concatenate them together. The cat command is often used to quickly view the contents of small text files, concatenate files, or …
Linux
Tcpdump command is very powerful to capture network packets with different tcpdump filters on Linux. This tutorial will show us how to isolate traffic with 20 advanced tcpdump examples—source IP, multiple interfaces, tcpdump all interfaces, multiple protocols, UDP, multiple ports, multiple hosts, tcp flags, port, port range. Captured data with different tcpdump options are generally …
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, …
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 …