I figure it out. There is no mcast routing setup by default, so add one using route: [514][valkyrie: testsuite]$ sudo route add -net 224.0.0.0/4 127.0.0.1 [514][valkyrie: testsuite]$ netstat -rn -f inet Routing tables Internet: Destination Gateway Flags Refs Use Netif Expire default 192.168.2.1 UGSc 31 36 en0 127 127.0.0.1 UCS 0 0 lo0 127.0.0.1 127.0.0.1 UH 7 20058 lo0 169.254 link#4 UCS 0 0 en0 192.168.2 link#4 UCS 2 0 en0 192.168.2.1 0:f:66:a0:60:7f UHLW 31 67 en0 1142 192.168.2.105 127.0.0.1 UHS 0 0 lo0 192.168.2.255 link#4 UHLWb 1 81 en0 224.0.0/4 127.0.0.1 UGS 3 288 lo0 [515][valkyrie: testsuite]$ ant -Dtest=org.jboss.test.naming.test.SimpleUnitTestCase one-test Buildfile: build.xml one-test: [delete] Deleting: /Users/svn/JBossHead/jboss-head/testsuite/output/log/test.log [junit] Running org.jboss.test.naming.test.SimpleUnitTestCase [junit] Tests run: 10, Failures: 0, Errors: 0, Time elapsed: 5.508 sec BUILD SUCCESSFUL Total time: 10 seconds