Debug on Console

Those who work with Linux servers, but also those who use Linux as a desktop every day knows that it is very useful to have a list of processes running on the machine with a list of resources they are using, to see who is eating all the memory or is using all the CPU, and the ps command is not exactly the most convenient. So we ‘ll see a series of programs that serve to show what’s happening in our system and who is using our resources. The first tool that you can use to get information is the  ps  command, yes i know, it’s not so handy but you are sure to have it installed in every machine and you can get quickly some information on the system: Get the top 10 CPU consuming process ps aux | sort -n -k 3 | tail -10 Get the top 10 memory consuming process ps aux | sort -n -k 4 | tail -10 Top In most Unix-like operating systems, the top command is a system monitor tool that produces a frequently-updated list of processes. By default, the processes are ordered by

Know what is happening in “real time” on your systems is in my opinion the basis to use and optimize your OS. On ArchLinux or better on GNU/Linux in general the  top  command can help us, this is a very useful system monitor that is really easy to use, and that can also allows us to understand why our OS suffers and which process use most resources. The command to be run on the terminal is: $ top And we’ll get a screen similar to the one on the right: Let’s see now every single row of this output to explain all the information found within the screen. 1° Row — top This first line indicates in order: current time (11:37:19) uptime of the machine (up 1 day, 1:25) users sessions logged in (3 users) average load on the system (load average: 0.02, 0.12, 0.07) the 3 values refer to the last minute, five minutes and 15 minutes. 2° Row – task The second row gives the following information: Processes running in totals (73 total) Processes running (2 runni

HOW TO INSTALL TCPDUMP IN LINUX Many of Linux distributions already shipped with  tcpdump  tool, if in case you don’t have it on systems, you can install it using following Yum command. # yum install tcpdump Once  tcpdump  tool is installed on systems, you can continue to browse following commands with their examples. 1. CAPTURE PACKETS FROM SPECIFIC INTERFACE The command screen will scroll up until you interrupt and when we execute tcpdump  command it will captures from all the interfaces, however with  -i  switch only capture from desire interface. # tcpdump -i eth0 tcpdump: verbose output suppressed, use -v or -vv for full protocol decode listening on eth0, link-type EN10MB (Ethernet), capture size 65535 bytes 11:33:31.976358 IP 172.16.25.126.ssh > 172.16.25.125.apwi-rxspooler: Flags [P.], seq 3500440357:3500440553, ack 3652628334, win 18760, length 196 11:33:31.976603 IP 172.16.25.125.apwi-rxspooler > 172.16.25.126.ssh: Flags [.], ack 196, win 64487, length 0 11:33:31.

Apache Tomcat  is an open source web server and servlet container developed by the  Apache Software Foundation . It implements the Java Servlet, JavaServer Pages (JSP), Java Unified Expression Language and Java WebSocket specifications from Sun Microsystems and provides a web server environment for Java code to run in. Binding Tomcat to IPv4 is necessary if we have our server not working due to the default binding of our tomcat server to IPv6. As we know IPv6 is the modern way of assigning IP address to a device and is not in complete practice these days but may come into practice in soon future. So, currently we don't need to switch our tomcat server to IPv6 due to no use and we should bind it to IPv4. Before thinking to bind to IPv4, we should make sure that we've got tomcat installed in our CentOS 7. Here's is a quick tutorial on  how to install tomcat 8 in CentOS 7.0 Server . 1. Switching to user tomcat First of all, we'll gonna switch user to  tomcat  user. We

In Apache 2.4 the authorization configuration setup has changed from previous versions. Satisfy, Order, Deny and Allow have all been deprecated and replaced with new  Require  directives. Below we've compiled some examples to guide you through the transition. If you are upgrading a server using the legacy authorization directives you can make them work quickly by enabling (it should be activated by default) mod_access_compat  in Apache: sudo a2enmod access_compat 1. Apache Documentation The documentation from Apache:  Upgrading to 2.4 from 2.2  provides the following basic examples. The old configuration settings are on the left, and the new ones for Apache 2.4 on the right: All requests are denied: Order deny,allow Deny from all Require all denied All requests are allowed: Order allow,deny Allow from all Require all granted Only hosts in the example.org domain are allowed access: Order Deny,Allow Deny from all Allow from example.org Requir