FAQ for the 'Security' Category

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Viewing 41-50 of 99 FAQ -

Linux Detecting / Checking Rootkits with Chkrootkit and rkhunter Software
Q. Most rootkits use the power of the kernel to hide themselves, they are only visible from within the kernel. How do I detect rootkits under CentOS or Debian Linux server?
How To Automate a Remote Login Using SSH

Q. How do I automate a remote login using ssh service? I’d like to login automatically to my remoter server called server.exmaple.com from my local Linux desktop system?
Linux Password Cracking: Explain unshadow and john commands ( john the ripper tool )
Q. Can you tell me more about unshadow and john command line tools? How does it protect my server from crackers?
Disable a Firewall In Red Hat Enterprise Linux

Q. How do I disable a firewall in RedHat Enterprise Linux / RHEL?
ICMP IP Network Scanning / Probing using a Shell Commands
Q. How do I check security of my network by running ICMP IP Network Scanning under FreeBSD / Linux? How do I subnet broadcast addresses? All I wanted to see if my firewall is working or not.
A. Internet Control Message Protocol (ICMP) one of the core protocols of the Internet protocol suite. It is chiefly [...]
How to: Open Ssh Port 22 on Linux APF Firewall under CentOS / RHEL
Q. I’d like to change ssh port from 22 to 2346. I changes the ssh port and reloaded OpenSSH but didn’t get through my firewall. I’m using APF firewall script under cPanel control panel? How do I open port 2346?
A. By default APF configured via /etc/apf/conf.apf file. All you have to do is login as [...]
How to: Log connections made by user for any service under Linux
Q. I’d like to log information about selected incoming and outgoing TCP/IP connections to a log file. For example, log connection made by user “tom” for the service ftp or ssh? How do I configure Linux to log connections?
A. You can write a perl or shell script to monitor and log all connection. [...]
Understanding Bash fork() bomb ~ :(){ :|:& };:
Q. Can you explain following bash code or bash fork() bomb?
:(){ :|:& };:
A. This is a bash function. It gets called recursively (recursive function). This is most horrible code for any Unix / Linux box. It is often used by sys admin to test user processes limitations (Linux process limits can be configured via [...]
How to Tunnel X Windows Securely over SSH
Q. How do I tunnel X Windows Securely over SSH? I’d like to run X program on my remote Linux server and get back display to Laptop computer connected by high speed internet?
A. A tunneling protocol is a network protocol which encapsulates a payload protocol, acting as a payload protocol. Reasons to tunnel include carrying [...]
How to: Allow telnet and ssh through iptables under Linux
Q. I run both RHEL / CentOS Linux server and by default firewall blocked out everything including telnet / ssh access. How do I allow telnet - port 23 and ssh port 22 thought Linux iptables firewall ?
A.By default firewall rules stored at /etc/sysconfig/iptables location / file under CentOS / RHEL. All you have to [...]