blog.up-link.ro android bsd linux unix & open-source world

29Jul/110

FreeBSD: How To Rename Network Interfaces

To rename a network interface under FreeBSD, invoke ifconfig command as root:

ifconfig bge1 name net1

Observe that the interface formerly known as bge1 is now net1. To keep the change after reboot, add the following lines to /etc/rc.conf:

ifconfig_bge1_name="net1"
ifconfig_net1="inet 192.168.0.1 netmask 255.255.255.0"

Print This Post Print This Post
28Jul/110

How To Add a nullroute (blackhole filtering)

In computer networking, a null route or blackhole route is a network route that goes nowhere. Matching packets are dropped (ignored) rather than forwarded, acting as a kind of very limited firewall. The act of using null routes is often called blackhole filtering.

Null routing has an advantage over classical firewalls since it is available on every potential network router (including all modern operating systems), and adds virtually no performance impact. Due to the nature of high-bandwidth routers, null routing can often sustain higher throughput than conventional firewalls. For this reason, null routes are often used on high-performance core routers to mitigate large-scale denial-of-service attacks before the packets reach a bottleneck, thus avoiding collateral damage from DDoS attacks — although the target of the attack will be inaccessible to anyone.

Print This Post Print This Post
18Jun/101

FreeBSD: How To Create a Network Bridge

A device that connects two networks together into two separate network segments without having to create IP subnets and use a router to connect the segments together is called a "bridge".

To create a bridge use ifconfig command:

ifconfig bridge create

A bridge interface is created and is automatically assigned a randomly generated Ethernet address.

Print This Post Print This Post
1Apr/102

How To change Ethernet network card speed and duplex settings in Linux

This tutorial will explain how to change network card speed and duplex settings in linux. It's working with any linux distributions like Fedora, CentOS, Debian, Ubuntu, etc.

ethtool is an Linux/Unix command allowing to modify the NIC parameters. ethtool can be used to query and change settings such as speed, negotiation and checksum offload on many network devices, especially Ethernet devices.

1. Install ethtool

Install ethtool in Fedora and CentOS:

# yum install ethtool

Install ethtool in Debian:

# apt-get install ethtool

Install ethtool in Ubuntu:

# sudo apt-get install ethtool

Print This Post Print This Post