Although it is a security risks, it is possible to make OpenSSH listens on multiple port. To do that, you need to edit /etc/ssh/sshd_config file. and enable the “GatewayPorts” option. AllowTcpForwarding no GatewayPorts yes X11Forwarding no #X11DisplayOffset 10 Look for the line that contain “Port 22”, and uncomment it if necessary, and add additional Port […]
Here’s an easy way to encrypt your file using OpenSSL. The general syntax is: openssl enc (cipher) -e -in (input file) -out (output file) so to encrypt a “plaintext.txt” file, using aes256, you only need to run this command: openssl enc aes256 -e -in plaintext.txt -out encrypted.txt Similarly, to decrypt the file, you can run […]
One of the factor that makes your system easily crackable is the weak password. PAM cracklib forces users to choose stronger password by analyzing the password strength, length and entropy. To enable pam_cracklib in Debian / Ubuntu operating system, you need to install libpam_cracklib: sudo apt-get install libpam_cracklib Then edit the “/etc/pam.d/common-password” file using your […]
Here’s how to setup public-key (or passwordless) authentication in Ubuntu or any other Linux based operating system that use OpenSSH. First make sure you’ve remote SSH server running and accepting connection. Then you need to generate ssh key on local server (I prefer RSA). You can enter passphrase for added security, or leave it blank […]
Secure HTTP (SSL/TLS) has become a must if you are planning to setup a website which includes user authentication (ie. login box) or sensitive data. HTTPS prevents the sensitive data from being transfered across the network in clear text where it is susceptible to being sniffed or altered. Here is the tutorial on how to […]
GPG or the GNU Privacy Guard is a free and open source software that implements OpenPGP public-key cryptography message format (RFC4880). You can use GPG to encrypt, decrypt, sign and verify files or emails. To use GPG, you need to generate the public-key/private-key pairs in your computer by running this command, and choose the default […]