When I tested mod_cluster in a environment with apache Mod_security, i noticed connection error or reset by peer for mod_cluster in jboss server.log. Connection is not establish because of Mod_security protocol_anomalies.
jboss error:
09:44:02,326 ERROR [DefaultMCMPHandler] [] Error [null: null: {4}] sending command ENABLE-APP to proxy xxx.xxx.xxx.xxx:80, configuration will be reset
09:44:02,330 ERROR [DefaultMCMPHandler] [] Error [null: null: {4}] sending command INFO to proxy yyy.yyy.yyy.yyy:80, configuration will be reset
apache with Mod_security error:
[error] [client xxx.xxx.xxx.xxx] ModSecurity: Warning. Operator EQ matched 0 at REQUEST_HEADERS. [file "/etc/httpd/modsecurity.d/modsecurity_crs_21_protocol_anomalies.conf"] [line "35"] [id "960008"] [msg "Request Missing a Host Header"] [severity "WARNING"] [tag "PROTOCOL_VIOLATION/MISSING_HEADER"] [hostname "srvbinhttp1.banka.dmz"] [uri "/"] [unique_id "yLGhrMCoAjUAABeRvuIAAAAA"]
[error] [client yyy.yyy.yyy.yyy] ModSecurity: Warning. Operator EQ matched 0 at REQUEST_HEADERS. [file "/etc/httpd/modsecurity.d/modsecurity_crs_21_protocol_anomalies.conf"] [line "35"] [id "960008"] [msg "Request Missing a Host Header"] [severity "WARNING"] [tag "PROTOCOL_VIOLATION/MISSING_HEADER"] [hostname "srvbinhttp1.banka.dmz"] [uri "/"] [unique_id "yLGhrMCoAjUAABeRvuIAAAAA"]
You shouldn't use mod_security on the VirtualHost where mod_cluster is configured. The mcmp protocol only looks like http.