How to set up a TFTP Server for your Cisco routers

In this article, I will show you how to set up a TFTP server so that your Cisco router can communicate with it.
The presence of a TFTP server is important. By using it, you can back up, restore or upgrade your router’s configuration and IOS. Let’s start.

1. Install a TFTP server

I almost got frustrated when my TFTP server from Fedora repository didn’t work even though I followed all the steps from here.

Everything was set. Firewall configuration was set. Everything that you can imagine regarding this was set. Ping from router to the tftp server was successful. But when I tried to back up my IOS, it never worked. The router gave me this message:

"error opening tftp://192.168.0.101/c2500-is-l.120-21.bin (undefined error)"

I checked with Wireshark/Ethereal. Basically, the router request was accepted by the TFTP server (which means that the TFTP server is running).

So, I changed the TFTP server. And this tutorial will be based on this TFTP server.I downloaded it from here:
http://sourceforge.net/project/showfiles.php?group_id=162512&package_id=183619&release_id=595399

Then, untar the package: tar -xzvf tftpservermt

My tips for you. Read the README file! It says you should go to tftpservermt and edit the “.ini” file. Under [home], you can set your home directory for your tftp-server. Also you have to set the read, write and overwrite permission.

This is what I did in my “.ini” file:

[HOME]
#You should specify home directory(s) here
#The home directory can be specified
#in two different ways, with alias or
#bare names without aliases. Using alias you
#can specify upto 8 directories like
#routers=c:/RouterImages/Images
#without alisas, only one directory can
#be specified, which will become root
#directory for tftp
#mixup of bare names and aliases not allowed
/home/fadil/tftpserver

….

#Next are the file operation permissions
#Clients can only read files if read is
#set to Y, default is Y
read=Y
#Clients can only create new files if write is
#set to Y, default is N
write=Y
#Clients can only overwrite existing files if
#overwrite is #set to Y, default is Y
overwrite=Y

IMPORTANT:
Make sure you only allow trusted clients to access your TFTP server (this is a good security practice). You don’t want everybody can connect to your TFTP server, right?! You can set the IPs of trusted clients under [ALLOWED-CLIENTS].

Then, move the “.ini” file to /etc.

2. Bring up the interface and assign an IP address to your router

You have to bring up the specific interface that you want your router to connect through, and assign IP address to that interface.

FirstRouter2507#config t
Enter configuration commands, one per line. End with CNTL/Z.
FirstRouter2507(config)#interface ethernet 0
FirstRouter2507(config-if)#ip address 192.168.0.100 255.255.255.0
FirstRouter2507(config-if)#no shutdown

3. Assign an IP address for your TFTP server. Make sure that your TFTP server’s IP and your router’s IP address are on the same subnet.

4. Connect your router and TFTP server with a cross-over cable (straight-through cable will do if your router supports smart MDI/MDI-X). For me, both cables work fine!

5. Ping the TFTP server from your router console. For example, my TFTP’s IP address is 192.168.0.101/24:


FirstRouter2507#ping 192.168.0.101

Type escape sequence to abort.
Sending 5, 100-byte ICMP Echos to 192.168.0.101, timeout is 2 seconds:
!!!!!
Success rate is 100 percent (5/5), round-trip min/avg/max = 1/2/4 ms


6. Execute the tftpserver. You go to tftpservermt directory. And execute (root privilege is needed) : ./tftpserver -v. You will see something similar like the following:

Starting TFTP...
alias / is mapped to /home/fadil/tftpserver/
listening on: 127.0.0.1:69
listening on: 192.168.0.101:69
permitted clients: all
server port range: any
max blksize: 65464
defult blksize: 512
default timeout: 3
file read allowed: Yes
file create allowed: Yes
file overwrite allowed: Yes
thread pool size: 1

Accepting requests..

Now we’re in business. Your tftp server is up and running. You can now back up, restore, or upgrade your router’s IOS or configuration.

From my router

FirstRouter2507#copy startup-config tftp:
Address or name of remote host []? 192.168.0.101
Destination filename [FirstRouter2507-confg]?
!!
1653 bytes copied in 0.236 secs (7004 bytes/sec)
FirstRouter2507#copy startup-config tftp:
Address or name of remote host []? 192.168.0.101
Destination filename [FirstRouter2507-confg]? jun3-2
!!
1653 bytes copied in 0.232 secs (7125 bytes/sec)

FirstRouter2507#copy tftp: ?
null: Copy to null: file system
nvram: Copy to nvram: file system
running-config Update (merge with) current system configuration
startup-config Copy to startup configuration
system: Copy to system: file system

FirstRouter2507#copy tftp: star
FirstRouter2507#copy tftp: startup-config
Address or name of remote host []? 192.168.0.101
Source filename []? FirstRouter2507-confg
Destination filename [startup-config]?
Accessing tftp://192.168.0.101/FirstRouter2507-confg...
Loading FirstRouter2507-confg from 192.168.0.101 (via Ethernet0): !
[OK - 1653 bytes]
[OK]
1653 bytes copied in 11.672 secs (142 bytes/sec)
FirstRouter2507#
00:17:39: %SYS-5-CONFIG_NV_I: Nonvolatile storage configured from tftp://192.168e
FirstRouter2507#


From the TFTP server

Starting TFTP...
alias / is mapped to /home/fadil/tftpserver/
listening on: 127.0.0.1:69
listening on: 192.168.0.101:69
permitted clients: all
server port range: any
max blksize: 65464
defult blksize: 512
default timeout: 3
file read allowed: Yes
file create allowed: Yes
file overwrite allowed: Yes
thread pool size: 1

Accepting requests..
Client 192.168.0.100:55470 /home/fadil/tftpserver/FirstRouter2507-confg, 4 Blocks Received
Client 192.168.0.100:58299 /home/fadil/tftpserver/jun3-2, 4 Blocks Received
Client 192.168.0.100:51063 /home/fadil/tftpserver/FirstRouter2507-confg, 4 Blocks Served
Client 192.168.0.100:57338 /home/fadil/tftpserver/FirstRouter2507-confg, Client 172.16.10.1:57338, Error Code 0 at Client, Session terminated
Client 192.168.0.100:54148 /home/fadil/tftpserver/FirstRouter2507-confg, 4 Blocks Served
Client 192.168.0.100:49507 /home/fadil/tftpserver/FirstRouter2507-confg, 4 Blocks Served


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