Sunday, September 13, 2009

create a fixed device for udev

i stole this from

fconfig eth0
eth0 Link encap:Ethernet HWaddr 00:AB:CD:12:34:56
RX packets:0 errors:0 dropped:0 overruns:0 frame:0
TX packets:3 errors:0 dropped:0 overruns:0 carrier:3
collisions:0 txqueuelen:1000
RX bytes:0 (0.0 b) TX bytes:180 (180.0 b)
Interrupt:185 Base address:0xc000

In the above example HWaddr is your MAC address 00:AB:CD:12:34:56

Using udev

Create a new file in the udev rules directory, e.g. /etc/udev/rules.d/010_netinterfaces.rules

In it specify the renaming in the following way for each interface on its own line

KERNEL="oldnameprefix*", SYSFS{address}=="MACaddress", NAME="newname"

where the oldnameprefix is typically eth. Note that in the MAC address, the hexadecimal digits should be in lowercase, otherwise udev fails to match them properly with the network interface.

You have quite a bit of freedom in choosing the new name, We recommend to keep it short and without any spaces or weird characters though. You can e.g. specify a fixed eth0, eth1, eth2 for specific MAC addresses, or you can name them after their use, or anything really. Remember that some applications that poke on a low level may dislike them not being called in the normal fashion of eth0, eth1..etc

Examples using udev

Example: Three network interfaces being present on a computer, setting a fixed eth0, eth1 and eth2 as their names.

KERNEL=="eth*", SYSFS{address}=="00:12:34:fe:dc:ba", NAME="eth0"
KERNEL=="eth*", SYSFS{address}=="00:56:78:98:76:54", NAME="eth1"
KERNEL=="eth*", SYSFS{address}=="00:90:ab:32:10:fe", NAME="eth2"Example: Three network interfaces (one Intel, one NVIDIA, and one 3Com) being present on a computer, naming them after the manufacturer of the interfaces.

KERNEL=="eth*", SYSFS{address}=="00:12:34:fe:dc:ba", NAME="eth-intel"
KERNEL=="eth*", SYSFS{address}=="00:56:78:98:76:54", NAME="eth-nv"
KERNEL=="eth*", SYSFS{address}=="00:90:ab:32:10:fe", NAME="eth-3com"

Updating network configuration

If you named the interfaces in a different fashion as they were named before, the network configuration needs to be updated for the new interface device names to be used.

Edit the /etc/network/interfaces file, and change all instances of the old names to the new names.

E.g. if you previously used eth0 and have renamed it newname, you'd replace all instances of eth0 in that file with newname

But if you just put a fixed eth0, eth1, ... as their names, you just need to make sure the one you want to have as the primary network interface is set to the one you want in the file.


Having renamed the existing eth0, eth1, and eth2 to eth-intel, eth-nv and eth-3com, choosing to use the eth-intel one as the primary interface

The /etc/network/interfaces file before changes

# The primary network interface
auto eth0
iface eth0 inet dhcp

# Currently unused network interfaces
iface eth1 inet dhcp
iface eth2 inet dhcpThe file after changes:

# The primary network interface
auto eth-intel
iface eth-intel inet dhcp

# Currently unused network interfaces
iface eth-nv inet dhcp
iface eth-3com inet dhcp

Reboot and verify your configuration

Reboot the computer and verify that the new network interface names are in use with e.g. ifconfig

#ifconfig newname

Where newname is the new interface name you specified. Repeat procedure for each one you renamed.

Friday, September 11, 2009

debian apt-get dist-upgrade makes login as root fail

i tried many rescue attempts
Linux init=/bin/sh
mount -o remount,rw /
but rejected new passwd ...

so then i found this
passwd -d root
passwd root
enter passwd twice and it works
i found this at

great rescue....

vpnc: receiving packet message too long

check the router eth1 it has mtu set too small to 576 need to reset it to 1500
so go to
add line
ifconfig eth0 mtu 1500
and done
hat tip: