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Packet Analyzer: 15 TCPDUMP Command Examples

Thanks the geek stuff tcpdump command is also called as packet analyzer. tcpdump command will work on most flavors of unix operating system. tcpdump allows us to save the packets that are captured, so that we can use it for future analysis. The saved file can be viewed by the same tcpdump command. We can also use open source software like wireshark to read the tcpdump pcap files. In this tcpdump tutorial, let us discuss some practical examples on how to use the tcpdump command. 1. Capture packets from a particular ethernet interface using tcpdump -i When you execute tcpdump… Continue Reading

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Oracle Database Startup and Shutdown Procedure

thanks the geek stuff How To Startup Oracle Database 1. Login to the system with oracle username Typical oracle installation will have oracle as username and dba as group. On Linux, do su to oracle as shown below. $ su – oracle 2. Connect to oracle sysdba Make sure ORACLE_SID and ORACLE_HOME are set properly as shown below. $ env | grep ORA ORACLE_SID=DEVDB ORACLE_HOME=/u01/app/oracle/product/10.2.0 You can connect using either “/ as sysdba” or an oracle account that has DBA privilege. $ sqlplus ‘/ as sysdba’ SQL*Plus: Release 10.2.0.3.0 – Production on Sun Jan 18 11:11:28 2009 Copyright (c) 1982,… Continue Reading

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9 Linux ethtool Examples to Manipulate Ethernet Card (NIC Card)

Thanks to the geek stuff 1. List Ethernet Device Properties When you execute ethtool command with a device name, it displays the following information about the ethernet device. # ethtool eth0 Settings for eth0: Supported ports: [ TP ] Supported link modes: 10baseT/Half 10baseT/Full 100baseT/Half 100baseT/Full 1000baseT/Full Supports auto-negotiation: Yes Advertised link modes: 10baseT/Half 10baseT/Full 100baseT/Half 100baseT/Full 1000baseT/Full Advertised auto-negotiation: Yes Speed: 100Mb/s Duplex: Full Port: Twisted Pair PHYAD: 1 Transceiver: internal Auto-negotiation: on Supports Wake-on: d Wake-on: d Link detected: yes This above ethtool output displays ethernet card properties such as speed, wake on, duplex and the link detection… Continue Reading

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Linux modprobe Command Examples to View, Install, Remove Modules

Thanks to the geek stuff modprobe utility is used to add loadable modules to the Linux kernel. You can also view and remove modules using modprobe command. Linux maintains /lib/modules/$(uname-r) directory for modules and its configuration files (except /etc/modprobe.conf and /etc/modprobe.d). In Linux kernel 2.6, the .ko modules are used instead of .o files since that has additional information that the kernel uses to load the modules. The example in this article are done with using modprobe on Ubuntu. 1. List Available Kernel Modules modprobe -l will display all available modules as shown below. $ modprobe -l | less kernel/arch/x86/kernel/cpu/mcheck/mce-inject.ko… Continue Reading

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UNIX / Linux: 10 Netstat Command Examples

Thanks to the geek stuff Netstat command displays various network related information such as network connections, routing tables, interface statistics, masquerade connections, multicast memberships etc., In this article, let us review 10 practical unix netstat command examples. 1. List All Ports (both listening and non listening ports) List all ports using netstat -a # netstat -a | more Active Internet connections (servers and established) Proto Recv-Q Send-Q Local Address Foreign Address State tcp 0 0 localhost:30037 *:* LISTEN udp 0 0 *:bootpc *:* Active UNIX domain sockets (servers and established) Proto RefCnt Flags Type State I-Node Path unix 2 [… Continue Reading

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RPM Command: 15 Examples to Install, Uninstall, Upgrade, Query RPM Packages

Thanks to think geek RPM stands for Red Hat Package Manager. With root privilege, you can use the rpm command with appropriate options to manage the RPM software packages. In this article, let us review 15 practical examples of rpm command. Let us take an rpm of Mysql Client and run through all our examples. 1. Installing a RPM package Using rpm -ivh RPM filename has packagename, version, release and architecture name. For example, In the MySQL-client-3.23.57-1.i386.rpm file: MySQL-client – Package Name 3.23.57 – Version 1 – Release i386 – Architecture When you install a RPM, it checks whether your… Continue Reading

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How to Backup Linux? 15 rsync Command Examples

Thanks to the geek stuff rsync is used to perform the backup operation in UNIX / Linux. rsync utility is used to synchronize the files and directories from one location to another in an effective way. Backup location could be on local server or on remote server. Important features of rsync Speed: First time, rsync replicates the whole content between the source and destination directories. Next time, rsync transfers only the changed blocks or bytes to the destination location, which makes the transfer really fast. Security: rsync allows encryption of data using ssh protocol during transfer. Less Bandwidth: rsync uses… Continue Reading