How To Upgrade, Backup, or Restore Cisco IOS on a Switch using a CentOS Linux TFTP Server

I recently purchased 3 used Cisco 3560 switches from Amazon for around $25 each and discovered that the IOS versions were not the same across them. So here’s a walk through of how I backed-up the IOS from one of the switches to a TFTP server, and then copied the IOS from the TFTP Server to a different switch.

Hardware:
Linux machine running CentOS 7
Cisco Catalyst 3560 series Switch

CentOS Configuration

Install packages

yum install tftp-server
yum install xinetd

Set static IP address

nmcli con add con-name switch_tftp type ethernet ifname enp3s0
     substitute 'enp3s0' with your connection or interface name
     run 'ip addr show' to determine interface name
nmcli con mod switch_tftp ipv4.address 192.168.1.1/24 
nmcli con mod switch_tftp ipv4.method manual
nmcli con mod switch_tftp connection.autoconnect no

Enable TFTP server

vim /etc/xinetd.d/tftp
     change ‘disable = yes’ to ‘disable = no’

Adjust TFTP folder write permissions

chmod 777 /var/lib/tftpboot

Create dummy file with write permissions (overwritten in later step)

touch /var/lib/tftpboot/switch_ios
chmod 666 /var/lib/tftpboot/switch_ios

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