Doing visudo you get nano instead of your favorite text editor?
Mine is vim therefore I issue:
DEBIAN/UBUNTU way
# update-alternatives --config editor
There are 4 alternatives which provide `editor'.
Selection Alternative
-----------------------------------------------
1 /usr/bin/vim.tiny
2 /bin/ed
*+ 3 /bin/nano
4 /usr/bin/vim.basic
Press enter to keep the default[*], or type selection number:
Selecting 4 I’m ready to use my full syntax colors when I edit any file.
OTHER DISTROS
Edit your .bashrc file and add the following:
EDITOR=vim
export EDITOR
Next login you will have your VIM working.
If you want to have it immediately and only for this session just type
# export EDITOR=vim
and press enter.
I’ve come across multiple ways of doing it but so far the best way is the following (I assume you are on i386 platform and you have access to the net):
1. Download boot.img.gz from Debian website
2. Download the net-install image choosing i386.
3. Plug your USB drive into a Linux PC, open the shell and type
$ dmesg
Last few lines should be like the following:
sd 7:0:0:0: [sdb] Attached SCSI removable disk
sd 8:0:0:0: [sdb] 4030464 512-byte logical blocks: (2.06 GB/1.92 GiB)
sd 8:0:0:0: [sdb] Write Protect is off
Now we know it has been mapped as sdb
4. Use zcat to load the boot.img.gz onto your USB drive
# zcat boot.img.gz > /dev/sdb
CAUTION!!! this will destroy the entire data on the USB drive, make sure you have done the backup.
If you get an error ensure the following:
- You are root (don’t use sudo)
- The USB drive it’s not mounted, if it is umount it before issuing the above command.
5. Now mount the USB drive and copy the net-inst.iso image on it.
All done! Now plug it into the box you want to setup and enjoy the old fashion Debian installer 
This tip might comes handy when you do a system check and you want to make sure you don’t check the same file twice.
Let’s pretend that our “file1″ is a conf file that needs review. As you can see the output of the command issued below shows that the file was last edited in June.
Today I want to check the file without editing it and make sure next time I won’t check it again:
$ ls -l
total 0
-rw-r--r-- 1 luca luca 290 2009-06-29 16:33 file1
Touch is an excellent tool in this case:
$ touch file1
$ ls -l
total 0
-rw-r--r-- 1 luca luca 0 2009-08-29 19:43 file1
The Modification Time has changed and so has the access time.
If you want to change just the modification time leaving the access time untouched try with the -m option
$ touch -m file1
$ ls -l
total 0
-rw-r--r-- 1 luca luca 0 2009-08-29 19:46 file1
$ stat file1
[..]
Access: 2009-08-29 19:43:45.000000000 +0100
Modify: 2009-08-29 19:46:15.000000000 +0100
Change: 2009-08-29 19:46:15.000000000 +0100
And -a is just for the Access Time.
Another interesting option is -t. It lets you set the time and the date with whatever you like. This is often used to do fishy things
$ touch -t 200701012301 file1
$ stat file1
[..]
Access: 2007-01-01 23:01:00.000000000 +0000
Modify: 2007-01-01 23:01:00.000000000 +0000
Change: 2009-08-29 19:52:26.000000000 +0100
All broadcasts messages are dropped by the router when it receives on an interface. This specific command is enables the router to convert the broadcast messages distended for a specific destination into unicast. This interface level command needs to be applied on the interface which the broadcast receives from.
R1(config-if)#ip helper-address 10.10.10.10
Also there are other options where you point the address to a vrf etc…
The following broadcasts are forwarded by default…
TIME – Port 37
TACACS – Port 49
DNS – Port 53
BOOTP/DHCP Server – Port 67
BOOTP/DHCP Client – Port 68
TFTP – Port 69
NetBIOS Name Service – Port 137
NetBios Datagram Service – Port 138
Other protocols can be forwarded by using the following Global config commanding…
R1(config)#ip forward-protocol udp ?
Use the ? to see the supported protocols. You may use the following command to remove a specific protocol being forwarded…
R1(config)#no ip forward-protocol udp ?
This is one of the BGP configuration I have came across on my lab…
no-export : This will keep the route inside the confederation, but not to any peers.
local-as : This will keep the route inside the AS, but not even to confederation peers.
no-export –> local-as –> no-advertise
If there is no confederation present, no-export will reflect the same result as local-as.