netwyman

Linux Firewall Tools The Linux kernel is part of every Linux distribution. This also includes a Linux firewall called   netfilter . You can control the Linux Firewall with the Command Line Utility   iptables . Debian-based distributions like Ubuntu or Knoppix have no predefined rules during the installation, so everything is allowed by default. With Enterprise Linux distributions such as Fedora, CentOS or RedHat, use ports have to be opened manually. The configuration of the Linux firewall can be adapted to your needs using   iptables . However, the syntax and handling of   iptables   is relatively complex, so there are several tools / scripts to configure   iptables . We will introduce you to a small selection here. Tools for the command line to configure your Linux firewall Arno’s Firewall   – Secure firewall for single and multi-homed systems. Very easy to configure, handy to manage and highly customizable. Ferm   –...

Some system administrators often block   ICMP   messages to their servers in order to hide the Linux boxes to outside world on rough networks or to prevent some kind of IP flooding and denial of service attacks. The most simple method to block   ping command   on Linux systems is by adding an   iptables   rule, as shown in the below example.   Iptables   is a part of Linux kernel   netfilter   and, usually, is installed by default in most Linux environments. # iptables -A INPUT --proto icmp -j DROP # iptables -L -n -v [List Iptables Rules] Another general method of blocking ICMP messages in your Linux system is to add the below kernel variable that will drop all ping packets. # echo “1” > /proc/sys/net/ipv4/icmp_echo_ignore_all In order to make the above rule permanent, append following line to   /etc/sysctl.conf   file and, subsequently, apply the rule with   sysctl   command. # echo “net.ipv...