Tag: iptables

  1. Random knowledge VIII.

    25 January 2007

    You're getting old if you consider sleeping until 0900 'sleeping in'.

    When configuring a firewall with IPTables you have to specify the protocol before the port number(s) in each command. Do this:

    iptables -A INPUT -s -p tcp --dport 22 -j ACCEPT

    and not this

    iptables -A INPUT -s --dport 22 -p tcp -j ACCEPT

    If you don't, you'll see error messages to the effect of "Unknown arg '--dport'"

    When writing Snort rules, there are a few things to keep in mind. First of all, rules come in two parts: the …


  2. Random knowledge III.

    25 January 2007

    Coding with a teddy bear in your lap helps immensely.

    IPtables for the v2.4 Linux kernel series doesn't understand virtual interfaces (a.k.a. IP Aliasing). If you've never seen this before you can take one interface, say eth0, and bind an IP address to it, for example Under the v2.4 kernel series you can bind more than one IP address to an interface, which creates a virtual network interface. If I bound a second address ( to our network interface above you'd see in the output of /sbin/ifconfig eth0 …