Security

The GHOST (CVE-2015-0235) is serious network function vulnerability in Glibc. How do I check and test if a my Linux based server is secure using command line options?

{ 13 comments }

A very serious security problem has been found in the GNU C Library (Glibc) called GHOST. How can I fix GHOST vulnerability and protect my Linux server against the attack? How do I verify that my server has been fixed against the Glibc GHOST vulnerability?

{ 94 comments }

I have Soekris single board communication embedded computers which is optimized for low power and network usage. The server has four Ethernet ports. I’ve installed PFSense firewall on it and configure WAN + LAN ports. How do I setup IPv4 software bridge using PFSense so that the rest of ports act as a network switch?

{ 2 comments }

I run a multi-user system. Most users access resources using ssh client. How to stop leaking process information to all users on Linux operating systems? How do I prevent users from seeing processes that do not belong to them on a Debian/Ubuntu/RHEL/CentOS Linux server?

{ 9 comments }

I run a web-server and I would like to log packets with un-routable source addresses on Linux operating system. How can I log spoofed packets on Debian / Ubuntu / CentOS / RHEL / Linux based server? How can I log a Martian packet (packet from Mars) on Linux operating systems?

{ 2 comments }

I am using NFS server version 4.x on a CentOS/RHEL based system. I’m mounting my shared /var/www/ directory on five Apache based nodes using the following syntax:

mount -t nfs4 -o rw,intr,hard,proto=tcp rocknas02:/httproot/www /var/www/

I noticed that due to bug in my app user can sometime upload executable or other device files to get out of chrooted Apache server. How can I prevent such security issues on a CentOS or RHEL based NFS client and sever setup?

{ 0 comments }

I am a small business and ecom site owner. I also run a WordPress based blog to connect with my customers. However, I get too much spam from certain IPs and net-blocks. How do I block access to certain url(s) such as example.com/blog/wp-comments-post.php for selected IP address and CIDRs? How do I allow everyone including IP address 1.2.3.4 to access my blog but block IP address 1.2.3.4 accessing only example.com/blog/wp-comments-post.php? How do I block POST requests for selected IPs/CIDR on nginx?

{ 1 comment }