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Bug #79767 Firewall rules on appear to be blocking source port 1024
Submitted: 2020-07-01 19:01 UTC Modified: 2020-08-10 16:28 UTC
Avg. Score:4.5 ± 0.5
Reproduced:4 of 4 (100.0%)
Same Version:3 (75.0%)
Same OS:4 (100.0%)
From: chkimes at github dot com Assigned:
Status: Closed Package: Systems problem
PHP Version: Irrelevant OS: Any
Private report: No CVE-ID: None
 [2020-07-01 19:01 UTC] chkimes at github dot com
1024 is not a reserved port, but many misconfigured firewall rules tend to include it and block outbound connections that use it as a source port. This is causing connection failures from Azure VMs, where the outbound load balancer often starts assigning ports from 1024 upward.

Test script:
From any fresh Azure VM *without a public IP assigned*:


Did your web server firewall rules recently change?


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 [2020-07-01 21:14 UTC]
-Package: Website problem +Package: Systems problem
 [2020-08-05 16:39 UTC] chkimes at github dot com
Is there any update for this? I have a small repro with this Action:

The first request uses source port 1024 and fails. The second request uses source port 1025 and succeeds. This has previously been indicative of incorrectly set up firewall rules on the target.
 [2020-08-10 16:28 UTC] chkimes at github dot com
-Status: Open +Status: Closed
 [2020-08-10 16:28 UTC] chkimes at github dot com
Firewall rules are now fixed
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