Follow the below steps to verify the integrity of the IOS software on Cisco IOS routers.

  1. Confirm the current IOS image the router is using to boot.

    router#show version
    <omited>
    System image file is "flash0:c3900-universalk9-mz.SPA.153-2.T.bin"
    <omited>
  2. Log into Cisco website and find the IOS image. Mouse over to get the MD5 checksumCisco MD5
  3. Issue verify command with hash from Cisco’s website. If you don’t enter the hash, the router’s IOS hash will be displayed for manual verification.
    verify /md5 flash0:c3900-universalk9-mz.SPA.153-2.T.bin 7727d9c4daa89d62bb2ff6bdb0905feb
  4. Router’s output if the IOS hash has been matched.
    Verified (flash0:c3900-universalk9-mz.SPA.153-2.T.bin) = 7727d9c4daa89d62bb2ff6bdb0905feb
  5. If the hash did not match, the following will be displayed.

    %Error verifying flash0:c3900-universalk9-mz.SPA.153-2.T.bin
    Computed signature = 7727d9c4daa89d62bb2ff6bdb0905feb
    Submitted signature = 7727d9c4daa89d62bb2ff6bdb0905fe