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ZPA Passive FTP - Directory Listing Timeout

Issue

  • FTP login works (TCP 21)

  • Directory listing fails

  • Session times out (~20s)

 

Root Cause

  • ZPA Health Reporting sends background probes to FTP data ports

  • Passive FTP uses random high ports per session

  • Probe hits the port first → server closes it

  • Actual client connection is rejected/reset

 

Resolution

Set Health Reporting = None on the Application Segment

  • Stops background probes

  • Allows only the real client connection

  • FTP works normally

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