Technical Documentation

Configuring Checksum Hashes for a Commit Script

You can configure one or more checksum hashes that can be used to verify the integrity of a commit script before the script runs on the router or switch.

To configure a checksum hash:

  1. Create the script.
  2. Place the script in the /var/db/scripts/commit directory on the router or switch.
  3. Run the script through one or more hash functions to calculate hash values.

    JUNOS supports MD5, SHA-1, and SHA-256 hash functions.

    user@host>file checksum md5 /var/db/scripts/commit/script1.slax
    MD5 (/var/db/scripts/commit/script1.slax) = 3af7884eb56e2d4489c2e49b26a39a97
    user@host>file checksum sha1 /var/db/scripts/commit/script1.slax
    SHA1 (/var/db/scripts/commit/script1.slax) = 00dc690fb08fb049577d012486c9a6dad34212c0
    user@host>file checksum sha-256 /var/db/scripts/commit/script1.slax
    SHA256 (/var/db/scripts/commit/script1.slax) = 150bf53383769f3bfedd41fe73320777f208d4fda81230cb27b8738
  4. Configure the script.
    [edit system scripts commit]user@host#set file script1.slax checksum md5 3af7884eb56e2d4489c2e49b26a39a97[edit system scripts commit]user@host#set file script1.slax checksum sha-1 00dc690fb08fb049577d012486c9a6dad34212c0[edit system scripts commit]user@host#set file script1.slax checksum sha-256 150bf53383769f3bfedd41fe73320777f208d4fda81230cb27b8738

    During the execution of the script, JUNOS recalculates the checksum value using the configured hash and verifies that the calculated value matches the configured value. If the values differ, the execution of the script fails. When you configure multiple checksum values with different hash algorithms, all the configured values must match the calculated values; otherwise, the script execution fails. The commit operation also fails.


Published: 2010-03-30