Security

how to read or view utmp, wtmp and btmp files in Linux/Unix

View utmp, wtmp and btmp files In Linux/Unix operating systems everything is logged some where. Most of the system logs are logged in to /var/log folder. This folder contains logs related to different services and applications. In this folder we have some files such as utmp, wtmp and btmp. These files contains all the details(…)

How to generate GPG key in Linux?

Generating GPG key in Linux Q. Recently when we are building a RPM package using rpm-build we come across a requirement to have GPG key inserted in to the package for security and authenticity of the rpm package, so that people will come to know it came from us. This prompted us to create our(…)

Basics of SELinux in Linux

Basics of SElinux What is SELinux? SELinux is a set of security policies/modules which are going to apply on the machine to improve the overall security of the machine. These are the Linux security modules(LSM) which are loaded in to kernel to improve security on accessing services/files which improve security. SELinux is short form of(…)

Up coming posts on DNS(Domain Name System/Server) in Linux

We are very much happy to announce that we started posting on DNS client and Server stuff on our blog for this month(Jan 2011). We already have some minor existing stuff related to DNS and troubleshooting it. Below are quick links to our existing DNS Server/Client stuff http://www.linuxnix.com/tag/dns-servers http://www.linuxnix.com/tag/dns Some of the DNS topics which are going(…)

What is trailing Plus indicates in drwxr-xr-x+ in Linux permissions

In our previous post we written about dot at the end of permissions this is one more special permissions where you will find + at the end of permissions field in ls -l command output. This is actually a small post, which is asked by one of the requester. This is a special permission in(…)

What is the meaning of trailing dot in drwxr-xr-x Linux file permissions?

Q. Today I am came across a strange permissions listing ie dot, What is meant by dot in file/folder permissions in drwxr-xr-x in Linux? This is actually a small post, which is asked by one of the requester. This is a special permission in Linux which is recently included. Some times you will be seeing(…)

Display date and time for commands executed in linux

We can always set time to the commands showed in history command. Why we require to set time for this? This is totally a security measure and used for troubleshooting/fingerprinting a security threat. history command sample output before setting this variable. 466  df -h 467  df 468  exit 469  nfsstat 470  find / -iname *.ppt(…)

How To Disable Iptables Firewall In Redhat/CentOS Linux

IPtable is a firewall application by default installed in all the Linux flavors. It is having great capabilities in blocking and unblocking content. Some times its required to disable iptables to troubleshooting network related configurations.  To disable iptables in Redhat/CentOS we have to use the following commands. #service iptables stop #service iptables save #chkconfig iptables off(…)

How To Enable Verbose Mode For SSH Logins?

How we can login to remote server through ssh? #ssh user@servername or #ssh -l user servername or #ssh ip-add So when you will execute the above command you will get the password prompt. But if you want to see what will happen when you execute ssh command you have to enable verbose or debugging mode.(…)

How to implement ip forwarding in Linux

IP forwarding is a concept to make Linux machine to send data from one network to other, this is same as a router(A router is a device to send packets from one point to other point depending on the packet destination/rules etc).  Why we need IP forwarding on a Linux machine? Ans : We need(…)