A quick guide to setting up a TFTP server in Ubuntu

The aim of this guide is to describe the process required to setup a TFTP server on a Linux PC. The main reason I require a TFTP server is for backing up configuration files and IOS's from Cisco devices.

Trivial File Transfer Protocol (TFTP) is a simple protocol to transfer files. It has been implemented on top of the User Datagram Protocol (UDP) using port number 69. TFTP is designed to be small and easy to implement, therefore, lacks most of the features of a regular FTP. TFTP only reads and writes files (or mail) from/to a remote server. It cannot list directories, and currently has no provisions for user authentication.

There are plenty of free TFTP server daemons available for download for Windows machines, but at home I run Linux, and wanted to setup a dedicated machine just for copying Cisco IOS's and configs onto.

TFTP is far from secure, so I do NOT recommend leaving this port open on a machine which has access to the Internet.

Also it should be noted that this guide is intentionally command line as that is where the magic happens!

I normally sudo su which will log you in with root privileges and prevent you from continually entering your password.

This is not best practice, but its my guide and I'm lazy. If you prefer, insert a “sudo” in front of every command and skip the sudo su command.

sudo su
apt-get update && apt-get install tftp-hpa tftpd-hpa

This will install the server

The default location for for TFTP files is /var/lib/tftpboot. You can set a different location later if you'd like, but you must chmod and chown the directory you choose.

sudo mkdir /var/lib/tftpboot
sudo chown nobody.nogroup /var/lib/tftpboot
sudo chmod 777 /var/lib/tftpboot

Edit the TFTP server configuration file to put the service in daemon mode and set a custom directory you may have chosen above.
You can do this using command line text editors like Vi or Emacs but I just use Gedit

gedit /etc/default/tftpd-hpa

 

This is where you can customise you TFTP server.

I chose to create my servers root directory in my home directory.

In my case that is /home/anon/
I called my root directory TFTProot.

So my tftpd-hpa file looks like this;

# /etc/default/tftpd-hpa

RUN_DAEMON="yes"
OPTIONS="-l -s /home/anon/TFTProot"

TFTP_USERNAME="tftp"
TFTP_DIRECTORY="/home/anon/TFTProot"
TFTP_ADDRESS="0.0.0.0:69"
TFTP_OPTIONS="--secure

Save the file and then be sure to create the directory required;

mkdir /home/anon/TFTProot
chown anon.anon /home/anon/TFTProot
chmod 777 /home/anon/TFTProot

As your logged in as root, the directory will also belong to root so chown the directory to your login account and group.

I also made the directory world rightable.. (probably not best practice, but it worked for me and avoided the dreaded “TFTP error 1”)

Once my directory structure was in place I restarted the daemon;

/etc/init.d/tftpd-hpa restart

You should now have a working TFTP server up and running.

Don't take my word for it, check...

netstat -a |grep tftp

udp 0 0 *:tftp *:*

Or another way to check would be to scan your PC. You can scan the loopback IP address using nmap like this;

nmap -sU 127.0.0.1

Starting Nmap 5.21 ( http://nmap.org ) at 2012-01-31 21:17 GMT

Nmap scan report for localhost.localdomain (127.0.0.1)

Host is up (0.13s latency).

Not shown: 994 closed ports

PORT STATE SERVICE

68/udp open|filtered dhcpc

69/udp open|filtered tftp

135/udp open|filtered msrpc

A few notes about usage.

Before you can send a file to the tftp server, it needs to exist in the tftp directory.
I'm not sure why, or if I'm doing something wrong, but I found the secret to a successful transfer is to create a empty file first.

touch filename 
chmod 777 /home/anon/TFTProot/filename
ls -al

-rwxrwxrwx  1 root   root        0 2012-01-31 21:37 filename 

Incidentally, if anyone reading this knows of a better way, I would be intrigued to know how?

It is at this point we are ready to send the file from our Cisco device;

router#copy run tftp
Address or name of remote host[]?192.168.2.2
Destination filename [router-config]? filename
!!
3974 bytes copied in 1.492 secs (2664 bytes/sec)
router#

At this point your running-config should be in the directory you've created.