Aircrack-ng for Debian Wheezy (testing)

Mar 17

TomLinux General, Networking, Wireless Comments Off

After discovering that Aircrack-ng isn’t currently included in Debian Wheezy (but it is in both Stable and Sid), I grabbed the latest version out of SVN (v1.1 – r2128) and built the package for my x86-64 system.

Source and compiled executables are available here.

I have included the necessary scripts and binary files in the ‘bin/’ directory. Copy these to /usr/local/sbin/ – so they will be easy to remove when the aircrack-ng packages becomes available in Wheezy.

IPv6 DNS Advertisements

Feb 20

TomIPv6, Linux System Administration, Networking Comments Off

DNS client configuration can be handled by the standard Router Advertisement Daemon (radvd) – apt-get install radvd

Edit /etc/radvd.conf on your Linux Router and insert the following at the end of the file to use Google’s DNS Caching server:

RDNS 2001:4860:4860::8888
{
};

On your Linux clients install rdnssd. To automatically add the advertised IPv6 DNS servers to your /etc/resolv.conf

The /etc/resolv.conf now contains both IPv4 and IPv6 entries. Typically a DHCP client is adding the IPv4 DNS server entries, this can be prevented by removing ‘domain-name-servers’ from the ‘request’ line in dhclient.conf

Net-SNMP writable attribute

Feb 09

TomLinux System Administration, Networking Comments Off

Solarwinds NMS verifies the SNMP write configuration of its nodes (agents) by attemping to set the ‘sysContact.0′ (1.3.6.1.2.1.1.4.0) value.

On Net-SNMP you must first configure the ‘rwcommunity’ setting in the snmpd.conf file. Do not set ‘sysContact’ value in snmpd.conf.

Configuring ‘sysContact’ (or any other ‘sys’ setting) in the configuration file, results in that value being set as read-only. You will not be able to remotely configure the value, and Solarwinds configuration tests will fail.

Instead set values like ‘sysContact’, ‘sysName’, ‘sysDecr’ etc, using the command snmpset included with net-snmp.

Multiple IPv6 Addresses per Interface

Mar 15

TomIPv6, Linux System Administration, Networking No Comments

Using ‘ifconfig’ on Debian Lenny, multiple IPv6 addresses can be added using entries in ‘/etc/network/interfaces’ with the ‘up’ and ‘down’ options. For example: 

iface eth0 inet6 static
        address 2001:41c8:1:5568::100
        netmask 64
        gateway fe80::1
        pre-up echo 0 > /proc/sys/net/ipv6/conf/eth0/autoconf
        up /sbin/ifconfig eth0 inet6 add 2001:41c8:1:5568::1:100/64
        up /sbin/ifconfig eth0 inet6 add 2001:41c8:1:5568::2:100/64
        down /sbin/ifconfig eth0 inet6 del 2001:41c8:1:5568::1:100/64
        down /sbin/ifconfig eth0 inet6 del 2001:41c8:1:5568::2:100/64

Emulating a network connection with packet drop

Feb 27

TomLinux General, Networking No Comments

IP packet drop can be easily emulated on any section of network using a Linux Bridge and a single iptables command:

iptables -t mangle -A FORWARD -m statistic --mode random --probability 0.01 -j DROP

(where probability is expressed as a value between 0 and 1)

If the intention is to emulate packet drop to the local Linux system not using a bridge, use the INPUT chain:

iptables -t mangle -A INPUT -m statistic --mode random --probability 0.01 -j DROP

To remove the random packet drop and restore the connection to normal operation either change -A to -D in the above commands, or flush the iptables with:
iptables -t mangle -F FORWARD or iptables -t mangle -F INPUT

Older Entries Newer Entries