Bug 69052 - httpd does not attempt an IPv6/IPv4 fallback in proxy mode
Summary: httpd does not attempt an IPv6/IPv4 fallback in proxy mode
Status: NEW
Alias: None
Product: Apache httpd-2
Classification: Unclassified
Component: mod_proxy_connect (show other bugs)
Version: 2.4.59
Hardware: PC Linux
: P2 normal (vote)
Target Milestone: ---
Assignee: Apache HTTPD Bugs Mailing List
URL:
Keywords:
Depends on:
Blocks:
 
Reported: 2024-05-26 22:01 UTC by Bjoern Voigt
Modified: 2024-05-26 22:01 UTC (History)
1 user (show)



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Description Bjoern Voigt 2024-05-26 22:01:18 UTC
If httpd is used in proxy mode (tested with HTTPS/mod_proxy_connect, proxy in forward mode), the proxy modules do not attempt an IPv6/IPv4 fallback.

This is an issue, if an URL hostname has both IPv6 and IPv4 addresses, but only the IPv4 address can be connected. (The IPv6 address connection attempt must give a connection refused ICMP result.)

The IPv6 test (https://ipv6-test.com/) shows the issue:

1) Test with Apache proxy enabled in Firefox:

IPv4 	Supported
IPv6 	Supported
Default 	IPv6
Fallback 	No
DNS4 + IP6 	Reachable
DNS6 + IP4 	Reachable
DNS6 + IP6 	Reachable

2) Test with direct Firefox connection:

IPv4 	Supported
IPv6 	Supported
Default 	IPv6
Fallback 	to IPv4 in < 1 second
DNS4 + IP6 	Reachable
DNS6 + IP4 	Reachable
DNS6 + IP6 	Reachable