Wildfly rejects calls due to a bug in Undertow with an UnknownHostException --------------------------------------------------------------------------- Key: WFLY-3878 URL: https://issues.jboss.org/browse/WFLY-3878 Project: WildFly Issue Type: Bug Components: Web (Undertow) Affects Versions: 8.1.0.Final Environment: All Reporter: Mayank Goyal Assignee: Stuart Douglas Fix For: 8.2.0.CR1, 9.0.0.Beta1 Refer to undertow commit: https://github.com/undertow-io/undertow/commit/204684cc41fc369f56bd0305a7... With proxy-address-forwarding="true" set in wildfly configuration & X-Forwarded-For headers passed in headers with additional proxies following behaviour can be noticed. For example with X-Forwarded-For set as "123.123.123.123, 210.210.210.210" following IP is reported to the application "123.123.123.12". Which is incorrect and has its own implications. With X-Forwarded-For set as "1.1.1.1, 2.2.2.2" an java.net.UnknownHostException is thrown in the undertow package. And the connection is terminated with an Internal server error returned to the caller.