Communication issues with hubs, robots, and probes

Document ID : KB000127522
Last Modified Date : 22/02/2019
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Issue:
Seeing communication errors whenever a probe configure GUI is opened from Infrastructure Manager running on on the primary hub and connected to the primary hub.  The robots are managed by a remote hub connected to a tunnel server via a hub tunnel.  The primary hub is also connected to the same tunnel server via a hub tunnel.
Environment:
UIM 8.51 (any release through 9.02)
hub 7.91 (any version through 7.97)
Cause:
Error messages similar to the following are seen in the tunnel client and tunnel server logs:

hub: sockWrite Failed: 000000000725AD90 <hub IP address>/<port> 10054 (rc = -1, sfd = 6368, lenleft = 246)
Resolution:
It would appear that there is a firewall that is interrupting the communication between the tunnel client hubs and the tunnel server hub

The keys to indicate that this might be a firewall issue are the "sockWrite Failed" message string and the lenleft value. Typically these are indicative of a firewall that shuts down the connection which it was still in use.

This typically occurs with firewalls that are "application aware".

The following is recommended for firewalls with application aware enabled:

The firewall rules put in place for UIM ports (48000-48050) should be:

Idle connection timeout: 7200
Max connection timeout: 7200
TCP Connection only : No application awareness (important)

Note: when application awareness is turned off the max connection & idle connection should be the same.