unix

0

SSH Keys 101

Posted on by jlim0930

If you have a centralized server where you manage many remote servers on you will most likely want to setup ssh keys so that you would not have to type in your password everytime. ssh comes with many utilities to generate handle and manage keys. this article will talk mainly about ssh-keygen, ssh-agent, ssh-copy-id, and ssh-add. Lets say you want to generate your keys you will issue ssh-keygen which will default to rsa or you can specify dsa by typing ssh-keygen -t dsa. It will prompt you for a passphrase to use. You will always want to select a passphase… Continue Reading →

0

Packet Analyzer: 15 TCPDUMP Command Examples

Posted on by jlim0930

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 →

0

Oracle Database Startup and Shutdown Procedure

Posted on by jlim0930

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 →

0

UNIX / Linux: 10 Netstat Command Examples

Posted on by jlim0930

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 →

0

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

Posted on by jlim0930

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 →

0

How to Backup Linux? 15 rsync Command Examples

Posted on by jlim0930

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 →