Avamar: NDMP Accelerator Node fails to connect to the NAS device on a random port
Summary: The NDMP Accelerator Node fails to connect to the NAS device on a random port with the error message: Unable to establish data connection to address. This issue is commonly seen after upgrades of the NDMP Accelerator. ...
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Symptoms
NDMP Accelerator Node failed to connect to the NAS device on a random port which led to NDMP backup failure.
avndmp Info <0000>: [snapup-/xxxxxx] Connecting to data socket on address x.x.x.x, port xxxxx.
avndmp Error <0000>: [snapup-/xxxxxx] Unable to establish data connection to address 'NAS device ip address or FQDN', port xxxx.
avndmp Error <0000>: [snapup-/xxxxxx] Backup for target /xxxxxx had errors.
avndmp Info <0000>: [snapup-/xxxxxx] Backup of '/xxxxxx' aborted. Error in NDMP session.
Cause
The Avamar Firewall service blocks some of the port ranges that the NAS filer randomly selects for the NDMP traffic.
Resolution
Follow the section "Add NAS to Avamar firewall" from the Dell Avamar NDMP Accelerator for NAS Systems user guide.
The NDMP user guides can be found on the Dell Support site.
This includes specific instructions for adding NAS clients to the Avamar Firewall. Configuration settings WILL remain after an upgrade.
The NDMP user guides can be found on the Dell Support site.
This includes specific instructions for adding NAS clients to the Avamar Firewall. Configuration settings WILL remain after an upgrade.
Affected Products
AvamarProducts
AvamarArticle Properties
Article Number: 000165840
Article Type: Solution
Last Modified: 07 Aug 2025
Version: 6
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