Linux Force or restart network card auto-negotiation with ethtool

Posted on in Categories CentOS, Howto, Linux, Networking, RedHat/Fedora Linux, Sys admin, Tips, Tuning last updated July 16, 2007

ethtool or mii-tool utility checks or sets the status of a network interface’s Media Independent Interface (MII) unit. Most fast ethernet adapters use an MII to autonegotiate link speed and duplex setting.

Due to software or hardware (network switch or Ethernet card ) error it may be possible that you need to restarts auto-negotiation on the specified ethernet device.

Restart autonegotiation

You don’t have to reboot Linux box, all you have to do is type the following command :
# ethtool -r eth0
Or you can use mii-tool (outdated, use ethtool only)
# mii-tool -r eth0
# tail -f /var/log/messages

Jul 16 09:34:25 smtp1 kernel: e1000: eth0: e1000_watchdog_task: NIC Link is Up 10 Mbps Full Duplex
Jul 16 09:34:25 smtp1 kernel: e1000: eth0: e1000_watchdog_task: 10/100 speed: disabling TSO

See also:

Iptables MAC Address Filtering

Posted on in Categories Iptables, Linux last updated December 15, 2010

LAN or wireless access can be filtered by using the MAC addresses of the devices transmitting within your network. A mac address is acronym for media access control address, is a unique address assigned to almost all-networking hardware such as Ethernet cards, routers, mobile phones, wireless cards and so on (see mac address at wikipedia for more information). This quick tutorial explains how to block or deny access using MAC address using iptables – Linux administration tool for IPv4 packet filtering and NAT.