diff --git a/scripts/base/frameworks/cluster/main.zeek b/scripts/base/frameworks/cluster/main.zeek
index 6620060fae..73e3cf541b 100644
--- a/scripts/base/frameworks/cluster/main.zeek
+++ b/scripts/base/frameworks/cluster/main.zeek
@@ -363,7 +363,9 @@ export {
 	## WebSocket server options to pass to :zeek:see:`Cluster::listen_websocket`.
 	type WebSocketServerOptions: record {
 		## The host address to listen on.
-		listen_host: string;
+		listen_host: string &optional &deprecated="Remove in v8.1: Use $listen_addr instead.";
+		## The address to listen on, cannot be used together with ``listen_host``.
+		listen_addr: addr &optional;
 		## The port the WebSocket server is supposed to listen on.
 		listen_port: port;
 		## The maximum event queue size for this server.
diff --git a/src/cluster/cluster.bif b/src/cluster/cluster.bif
index 83a7cd8f3e..011e53b245 100644
--- a/src/cluster/cluster.bif
+++ b/src/cluster/cluster.bif
@@ -1,6 +1,7 @@
 %%{
 #include <string>
 
+#include "zeek/IPAddr.h"
 #include "zeek/cluster/Backend.h"
 #include "zeek/cluster/BifSupport.h"
 #include "zeek/cluster/Manager.h"
@@ -192,8 +193,32 @@ function Cluster::__listen_websocket%(options: WebSocketServerOptions%): bool
 		tls_options_rec->GetFieldOrDefault<zeek::StringVal>("ciphers")->ToStdString(),
 	};
 
-	struct ServerOptions server_options {
-		options_rec->GetField<zeek::StringVal>("listen_host")->ToStdString(),
+	std::string listen_addr;
+
+	// Backwards compat for listen_host if listen_addr isn't set.
+	if ( options_rec->HasField("listen_host") ) {
+		if ( options_rec->HasField("listen_addr") ) {
+			zeek::emit_builtin_error("cannot use both listen_addr and listen_host");
+			return zeek::val_mgr->False();
+		}
+
+		auto host = options_rec->GetField<zeek::StringVal>("listen_host")->ToStdString();
+		if ( ! zeek::IPAddr::IsValid(host.c_str()) ) {
+			zeek::emit_builtin_error("invalid listen_host");
+			return zeek::val_mgr->False();
+		}
+
+		listen_addr = std::move(host);
+
+	} else if ( options_rec->HasField("listen_addr") ) {
+		listen_addr = options_rec->GetField<zeek::AddrVal>("listen_addr")->AsAddr().AsString();
+	} else {
+		zeek::emit_builtin_error("missing listen_host field");
+		return zeek::val_mgr->False();
+	}
+
+	struct ServerOptions server_options{
+		listen_addr,
 		static_cast<uint16_t>(options_rec->GetField<zeek::PortVal>("listen_port")->Port()),
 	};
 
diff --git a/testing/btest/Baseline.zam/cluster.websocket.listen-idempotent/.stderr b/testing/btest/Baseline.zam/cluster.websocket.listen-idempotent/.stderr
index f55de0446c..b46f38d9fd 100644
--- a/testing/btest/Baseline.zam/cluster.websocket.listen-idempotent/.stderr
+++ b/testing/btest/Baseline.zam/cluster.websocket.listen-idempotent/.stderr
@@ -1,5 +1,5 @@
 ### BTest baseline data generated by btest-diff. Do not edit. Use "btest -U/-u" to update. Requires BTest >= 0.63.
-error in <...>/main.zeek, line 673: Already listening on 127.0.0.1:<port> (Cluster::__listen_websocket(ws_opts_x))
-error in <...>/main.zeek, line 673: Already listening on 127.0.0.1:<port> (Cluster::__listen_websocket(ws_opts_wss_port))
-error in <...>/main.zeek, line 673: Already listening on 127.0.0.1:<port> (Cluster::__listen_websocket(ws_opts_qs))
+error in <...>/main.zeek, line 675: Already listening on 127.0.0.1:<port> (Cluster::__listen_websocket(ws_opts_x))
+error in <...>/main.zeek, line 675: Already listening on 127.0.0.1:<port> (Cluster::__listen_websocket(ws_opts_wss_port))
+error in <...>/main.zeek, line 675: Already listening on 127.0.0.1:<port> (Cluster::__listen_websocket(ws_opts_qs))
 received termination signal
diff --git a/testing/btest/Baseline.zam/cluster.websocket.one-ipv6-deprecated/..manager..stderr b/testing/btest/Baseline.zam/cluster.websocket.one-ipv6-deprecated/..manager..stderr
new file mode 100644
index 0000000000..9cdf7df5e4
--- /dev/null
+++ b/testing/btest/Baseline.zam/cluster.websocket.one-ipv6-deprecated/..manager..stderr
@@ -0,0 +1,4 @@
+### BTest baseline data generated by btest-diff. Do not edit. Use "btest -U/-u" to update. Requires BTest >= 0.63.
+warning in ../manager.zeek, line 12: deprecated (Cluster::WebSocketServerOptions$listen_host): Remove in v8.1: Use $listen_addr instead. ((coerce [$listen_host=::1, $listen_port=to_port(getenv(WEBSOCKET_PORT))] to Cluster::WebSocketServerOptions))
+warning in <no location>: deprecated (Cluster::WebSocketServerOptions$listen_host): Remove in v8.1: Use $listen_addr instead. (Cluster::WebSocketServerOptions($listen_host=::1, $listen_port=to_port(getenv(WEBSOCKET_PORT))))
+received termination signal
diff --git a/testing/btest/Baseline.zam/cluster.websocket.tls-usage-error/.stderr b/testing/btest/Baseline.zam/cluster.websocket.tls-usage-error/.stderr
index 49a7f00389..66e26e28c6 100644
--- a/testing/btest/Baseline.zam/cluster.websocket.tls-usage-error/.stderr
+++ b/testing/btest/Baseline.zam/cluster.websocket.tls-usage-error/.stderr
@@ -1,3 +1,3 @@
 ### BTest baseline data generated by btest-diff. Do not edit. Use "btest -U/-u" to update. Requires BTest >= 0.63.
-error in <...>/main.zeek, line 673: Invalid tls_options: No key_file field (Cluster::__listen_websocket(Cluster::options.0))
-error in <...>/main.zeek, line 673: Invalid tls_options: No cert_file field (Cluster::__listen_websocket(Cluster::options.3))
+error in <...>/main.zeek, line 675: Invalid tls_options: No key_file field (Cluster::__listen_websocket(Cluster::options.0))
+error in <...>/main.zeek, line 675: Invalid tls_options: No cert_file field (Cluster::__listen_websocket(Cluster::options.3))
diff --git a/testing/btest/Baseline/cluster.websocket.one-ipv6-deprecated/..client..stderr b/testing/btest/Baseline/cluster.websocket.one-ipv6-deprecated/..client..stderr
new file mode 100644
index 0000000000..49d861c74c
--- /dev/null
+++ b/testing/btest/Baseline/cluster.websocket.one-ipv6-deprecated/..client..stderr
@@ -0,0 +1 @@
+### BTest baseline data generated by btest-diff. Do not edit. Use "btest -U/-u" to update. Requires BTest >= 0.63.
diff --git a/testing/btest/Baseline/cluster.websocket.one-ipv6-deprecated/..client.out b/testing/btest/Baseline/cluster.websocket.one-ipv6-deprecated/..client.out
new file mode 100644
index 0000000000..c2f4ea81db
--- /dev/null
+++ b/testing/btest/Baseline/cluster.websocket.one-ipv6-deprecated/..client.out
@@ -0,0 +1,12 @@
+### BTest baseline data generated by btest-diff. Do not edit. Use "btest -U/-u" to update. Requires BTest >= 0.63.
+Connected
+Sending ping 0
+topic /test/pings event name pong args [{'@data-type': 'string', 'data': 'my-message'}, {'@data-type': 'count', 'data': 1}]
+Sending ping 1
+topic /test/pings event name pong args [{'@data-type': 'string', 'data': 'my-message'}, {'@data-type': 'count', 'data': 2}]
+Sending ping 2
+topic /test/pings event name pong args [{'@data-type': 'string', 'data': 'my-message'}, {'@data-type': 'count', 'data': 3}]
+Sending ping 3
+topic /test/pings event name pong args [{'@data-type': 'string', 'data': 'my-message'}, {'@data-type': 'count', 'data': 4}]
+Sending ping 4
+topic /test/pings event name pong args [{'@data-type': 'string', 'data': 'my-message'}, {'@data-type': 'count', 'data': 5}]
diff --git a/testing/btest/Baseline/cluster.websocket.one-ipv6-deprecated/..manager..stderr b/testing/btest/Baseline/cluster.websocket.one-ipv6-deprecated/..manager..stderr
new file mode 100644
index 0000000000..38376fb320
--- /dev/null
+++ b/testing/btest/Baseline/cluster.websocket.one-ipv6-deprecated/..manager..stderr
@@ -0,0 +1,3 @@
+### BTest baseline data generated by btest-diff. Do not edit. Use "btest -U/-u" to update. Requires BTest >= 0.63.
+warning in ../manager.zeek, line 12: deprecated (Cluster::WebSocketServerOptions$listen_host): Remove in v8.1: Use $listen_addr instead. ((coerce [$listen_host=::1, $listen_port=to_port(getenv(WEBSOCKET_PORT))] to Cluster::WebSocketServerOptions))
+received termination signal
diff --git a/testing/btest/Baseline/cluster.websocket.one-ipv6-deprecated/..manager.out b/testing/btest/Baseline/cluster.websocket.one-ipv6-deprecated/..manager.out
new file mode 100644
index 0000000000..ae19b33c56
--- /dev/null
+++ b/testing/btest/Baseline/cluster.websocket.one-ipv6-deprecated/..manager.out
@@ -0,0 +1,8 @@
+### BTest baseline data generated by btest-diff. Do not edit. Use "btest -U/-u" to update. Requires BTest >= 0.63.
+Cluster::websocket_client_added, [/test/pings, /zeek/wstest/ws1/]
+got ping: ping 0, 0
+got ping: ping 1, 1
+got ping: ping 2, 2
+got ping: ping 3, 3
+got ping: ping 4, 4
+Cluster::websocket_client_lost
diff --git a/testing/btest/Baseline/cluster.websocket.one-ipv6/..client..stderr b/testing/btest/Baseline/cluster.websocket.one-ipv6/..client..stderr
new file mode 100644
index 0000000000..49d861c74c
--- /dev/null
+++ b/testing/btest/Baseline/cluster.websocket.one-ipv6/..client..stderr
@@ -0,0 +1 @@
+### BTest baseline data generated by btest-diff. Do not edit. Use "btest -U/-u" to update. Requires BTest >= 0.63.
diff --git a/testing/btest/Baseline/cluster.websocket.one-ipv6/..client.out b/testing/btest/Baseline/cluster.websocket.one-ipv6/..client.out
new file mode 100644
index 0000000000..c2f4ea81db
--- /dev/null
+++ b/testing/btest/Baseline/cluster.websocket.one-ipv6/..client.out
@@ -0,0 +1,12 @@
+### BTest baseline data generated by btest-diff. Do not edit. Use "btest -U/-u" to update. Requires BTest >= 0.63.
+Connected
+Sending ping 0
+topic /test/pings event name pong args [{'@data-type': 'string', 'data': 'my-message'}, {'@data-type': 'count', 'data': 1}]
+Sending ping 1
+topic /test/pings event name pong args [{'@data-type': 'string', 'data': 'my-message'}, {'@data-type': 'count', 'data': 2}]
+Sending ping 2
+topic /test/pings event name pong args [{'@data-type': 'string', 'data': 'my-message'}, {'@data-type': 'count', 'data': 3}]
+Sending ping 3
+topic /test/pings event name pong args [{'@data-type': 'string', 'data': 'my-message'}, {'@data-type': 'count', 'data': 4}]
+Sending ping 4
+topic /test/pings event name pong args [{'@data-type': 'string', 'data': 'my-message'}, {'@data-type': 'count', 'data': 5}]
diff --git a/testing/btest/Baseline/cluster.websocket.one-ipv6/..manager..stderr b/testing/btest/Baseline/cluster.websocket.one-ipv6/..manager..stderr
new file mode 100644
index 0000000000..e3f6131b1d
--- /dev/null
+++ b/testing/btest/Baseline/cluster.websocket.one-ipv6/..manager..stderr
@@ -0,0 +1,2 @@
+### BTest baseline data generated by btest-diff. Do not edit. Use "btest -U/-u" to update. Requires BTest >= 0.63.
+received termination signal
diff --git a/testing/btest/Baseline/cluster.websocket.one-ipv6/..manager.out b/testing/btest/Baseline/cluster.websocket.one-ipv6/..manager.out
new file mode 100644
index 0000000000..ae19b33c56
--- /dev/null
+++ b/testing/btest/Baseline/cluster.websocket.one-ipv6/..manager.out
@@ -0,0 +1,8 @@
+### BTest baseline data generated by btest-diff. Do not edit. Use "btest -U/-u" to update. Requires BTest >= 0.63.
+Cluster::websocket_client_added, [/test/pings, /zeek/wstest/ws1/]
+got ping: ping 0, 0
+got ping: ping 1, 1
+got ping: ping 2, 2
+got ping: ping 3, 3
+got ping: ping 4, 4
+Cluster::websocket_client_lost
diff --git a/testing/btest/Baseline/cluster.websocket.tls-usage-error/.stderr b/testing/btest/Baseline/cluster.websocket.tls-usage-error/.stderr
index 46b508db58..9acc82d0db 100644
--- a/testing/btest/Baseline/cluster.websocket.tls-usage-error/.stderr
+++ b/testing/btest/Baseline/cluster.websocket.tls-usage-error/.stderr
@@ -1,3 +1,3 @@
 ### BTest baseline data generated by btest-diff. Do not edit. Use "btest -U/-u" to update. Requires BTest >= 0.63.
-error in <...>/tls-usage-error.zeek, line 17: Invalid tls_options: No key_file field (Cluster::listen_websocket((coerce [$listen_host=127.0.0.1, $listen_port=1234/tcp, $tls_options=tls_options_no_key] to Cluster::WebSocketServerOptions)))
-error in <...>/tls-usage-error.zeek, line 18: Invalid tls_options: No cert_file field (Cluster::listen_websocket((coerce [$listen_host=127.0.0.1, $listen_port=1234/tcp, $tls_options=tls_options_no_cert] to Cluster::WebSocketServerOptions)))
+error in <...>/tls-usage-error.zeek, line 17: Invalid tls_options: No key_file field (Cluster::listen_websocket((coerce [$listen_addr=127.0.0.1, $listen_port=1234/tcp, $tls_options=tls_options_no_key] to Cluster::WebSocketServerOptions)))
+error in <...>/tls-usage-error.zeek, line 18: Invalid tls_options: No cert_file field (Cluster::listen_websocket((coerce [$listen_addr=127.0.0.1, $listen_port=1234/tcp, $tls_options=tls_options_no_cert] to Cluster::WebSocketServerOptions)))
diff --git a/testing/btest/Files/ws/wstest.py b/testing/btest/Files/ws/wstest.py
index fa746c882b..9373f006d2 100644
--- a/testing/btest/Files/ws/wstest.py
+++ b/testing/btest/Files/ws/wstest.py
@@ -43,6 +43,7 @@ WS_PORT = (
 
 # IPv4 non-secure WebSocker URL for version 1
 WS4_URL_V1 = f"ws://127.0.0.1:{WS_PORT}/v1/messages/json"
+WS6_URL_V1 = f"ws://[::1]:{WS_PORT}/v1/messages/json"
 
 DEFAULT_RECV_TIMEOUT = 0.1
 OWN_TOPIC_PREFIX = "/zeek/wstest"
diff --git a/testing/btest/cluster/websocket/bad-event-args.zeek b/testing/btest/cluster/websocket/bad-event-args.zeek
index 323614d312..ae72dfdbb6 100644
--- a/testing/btest/cluster/websocket/bad-event-args.zeek
+++ b/testing/btest/cluster/websocket/bad-event-args.zeek
@@ -35,7 +35,7 @@ global pong: event(msg: string, c: count) &is_used;
 event zeek_init()
 	{
 	Cluster::subscribe("/zeek/event/my_topic");
-	Cluster::listen_websocket([$listen_host="127.0.0.1", $listen_port=to_port(getenv("WEBSOCKET_PORT"))]);
+	Cluster::listen_websocket([$listen_addr=127.0.0.1, $listen_port=to_port(getenv("WEBSOCKET_PORT"))]);
 	}
 
 event ping(msg: string, n: count) &is_used
diff --git a/testing/btest/cluster/websocket/bad-subscriptions.zeek b/testing/btest/cluster/websocket/bad-subscriptions.zeek
index be2cd473f4..1124d64452 100644
--- a/testing/btest/cluster/websocket/bad-subscriptions.zeek
+++ b/testing/btest/cluster/websocket/bad-subscriptions.zeek
@@ -35,7 +35,7 @@ global pong: event(msg: string, c: count) &is_used;
 event zeek_init()
 	{
 	Cluster::subscribe("/zeek/event/my_topic");
-	Cluster::listen_websocket([$listen_host="127.0.0.1", $listen_port=to_port(getenv("WEBSOCKET_PORT"))]);
+	Cluster::listen_websocket([$listen_addr=127.0.0.1, $listen_port=to_port(getenv("WEBSOCKET_PORT"))]);
 	}
 
 global added = 0;
diff --git a/testing/btest/cluster/websocket/bad-url.zeek b/testing/btest/cluster/websocket/bad-url.zeek
index 1e6349b25a..52afa00350 100644
--- a/testing/btest/cluster/websocket/bad-url.zeek
+++ b/testing/btest/cluster/websocket/bad-url.zeek
@@ -37,7 +37,7 @@ global pong: event(msg: string, c: count) &is_used;
 event zeek_init()
 	{
 	Cluster::subscribe("/zeek/event/my_topic");
-	Cluster::listen_websocket([$listen_host="127.0.0.1", $listen_port=to_port(getenv("WEBSOCKET_PORT"))]);
+	Cluster::listen_websocket([$listen_addr=127.0.0.1, $listen_port=to_port(getenv("WEBSOCKET_PORT"))]);
 	}
 
 event ping(msg: string, n: count) &is_used
diff --git a/testing/btest/cluster/websocket/broker/manager-recvs.zeek b/testing/btest/cluster/websocket/broker/manager-recvs.zeek
index 3bc6318c24..5ec20c1d82 100644
--- a/testing/btest/cluster/websocket/broker/manager-recvs.zeek
+++ b/testing/btest/cluster/websocket/broker/manager-recvs.zeek
@@ -42,7 +42,7 @@ event zeek_init()
 	Cluster::subscribe("/test/pings/");
 
 	Cluster::listen_websocket([
-		$listen_host="127.0.0.1",
+		$listen_addr=127.0.0.1,
 		$listen_port=to_port(getenv("WEBSOCKET_PORT")),
 	]);
 	}
diff --git a/testing/btest/cluster/websocket/broker/manager-sends.zeek b/testing/btest/cluster/websocket/broker/manager-sends.zeek
index dd39916b49..c37448f91c 100644
--- a/testing/btest/cluster/websocket/broker/manager-sends.zeek
+++ b/testing/btest/cluster/websocket/broker/manager-sends.zeek
@@ -40,7 +40,7 @@ global lost = 0;
 event zeek_init()
 	{
 	Cluster::listen_websocket([
-		$listen_host="127.0.0.1",
+		$listen_addr=127.0.0.1,
 		$listen_port=to_port(getenv("WEBSOCKET_PORT")),
 	]);
 	}
diff --git a/testing/btest/cluster/websocket/broker/manager-worker-ping-pong.zeek b/testing/btest/cluster/websocket/broker/manager-worker-ping-pong.zeek
index 614f5a47b2..87b704112e 100644
--- a/testing/btest/cluster/websocket/broker/manager-worker-ping-pong.zeek
+++ b/testing/btest/cluster/websocket/broker/manager-worker-ping-pong.zeek
@@ -76,7 +76,7 @@ event Cluster::node_up(name: string, id: string)
 	# Delay listening on WebSocket clients until worker-1 is around.
 	if ( name == "worker-1" )
 		Cluster::listen_websocket([
-			$listen_host="127.0.0.1",
+			$listen_addr=127.0.0.1,
 			$listen_port=to_port(getenv("WEBSOCKET_PORT"))
 		]);
 	}
diff --git a/testing/btest/cluster/websocket/broker/no-subscriptions.zeek b/testing/btest/cluster/websocket/broker/no-subscriptions.zeek
index e540085f5d..3bedb087b7 100644
--- a/testing/btest/cluster/websocket/broker/no-subscriptions.zeek
+++ b/testing/btest/cluster/websocket/broker/no-subscriptions.zeek
@@ -32,7 +32,7 @@ redef Broker::disable_ssl = T;
 event zeek_init()
 	{
 	Cluster::subscribe("/test/pings");
-	Cluster::listen_websocket([$listen_host="127.0.0.1", $listen_port=to_port(getenv("WEBSOCKET_PORT"))]);
+	Cluster::listen_websocket([$listen_addr=127.0.0.1, $listen_port=to_port(getenv("WEBSOCKET_PORT"))]);
 	}
 
 global ping_count = 0;
diff --git a/testing/btest/cluster/websocket/broker/oneshot.zeek b/testing/btest/cluster/websocket/broker/oneshot.zeek
index b029caa814..ed100c28d2 100644
--- a/testing/btest/cluster/websocket/broker/oneshot.zeek
+++ b/testing/btest/cluster/websocket/broker/oneshot.zeek
@@ -36,7 +36,7 @@ global ping: event(msg: string, c: count) &is_used;
 event zeek_init()
 	{
 	Cluster::subscribe("/test/pings");
-	Cluster::listen_websocket([$listen_host="127.0.0.1", $listen_port=to_port(getenv("WEBSOCKET_PORT"))]);
+	Cluster::listen_websocket([$listen_addr=127.0.0.1, $listen_port=to_port(getenv("WEBSOCKET_PORT"))]);
 	}
 
 event ping(msg: string, n: count) &is_used
diff --git a/testing/btest/cluster/websocket/cluster-log.zeek b/testing/btest/cluster/websocket/cluster-log.zeek
index 2f7ba20fc6..0cb1a40be0 100644
--- a/testing/btest/cluster/websocket/cluster-log.zeek
+++ b/testing/btest/cluster/websocket/cluster-log.zeek
@@ -43,7 +43,7 @@ global pong: event(msg: string, c: count) &is_used;
 event zeek_init()
 	{
 	Cluster::subscribe("/test/manager");
-	Cluster::listen_websocket([$listen_host="127.0.0.1", $listen_port=to_port(getenv("WEBSOCKET_PORT"))]);
+	Cluster::listen_websocket([$listen_addr=127.0.0.1, $listen_port=to_port(getenv("WEBSOCKET_PORT"))]);
 	}
 
 event ping(msg: string, n: count) &is_used
diff --git a/testing/btest/cluster/websocket/listen-idempotent.zeek b/testing/btest/cluster/websocket/listen-idempotent.zeek
index e187386ca3..7aea163b8b 100644
--- a/testing/btest/cluster/websocket/listen-idempotent.zeek
+++ b/testing/btest/cluster/websocket/listen-idempotent.zeek
@@ -20,20 +20,20 @@ event zeek_init()
 	local ws_port = to_port(getenv("WEBSOCKET_PORT"));
 	local wss_port = to_port(getenv("WEBSOCKET_SECURE_PORT"));
 
-	local ws_opts = Cluster::WebSocketServerOptions($listen_host="127.0.0.1", $listen_port=ws_port);
+	local ws_opts = Cluster::WebSocketServerOptions($listen_addr=127.0.0.1, $listen_port=ws_port);
 	local ws_opts_x = copy(ws_opts);
 	ws_opts_x$tls_options = tls_options;
 
-	local ws_opts_wss_port = Cluster::WebSocketServerOptions($listen_host="127.0.0.1", $listen_port=wss_port);
+	local ws_opts_wss_port = Cluster::WebSocketServerOptions($listen_addr=127.0.0.1, $listen_port=wss_port);
 
 	local ws_tls_opts = Cluster::WebSocketServerOptions(
-		$listen_host="127.0.0.1",
+		$listen_addr=127.0.0.1,
 		$listen_port=wss_port,
 		$tls_options=tls_options,
 	);
 	# Same as ws_tls_opts
 	local ws_tls_opts_copy = Cluster::WebSocketServerOptions(
-		$listen_host="127.0.0.1",
+		$listen_addr=127.0.0.1,
 		$listen_port=wss_port,
 		$tls_options=tls_options_2,
 	);
diff --git a/testing/btest/cluster/websocket/one-ipv6-deprecated.zeek b/testing/btest/cluster/websocket/one-ipv6-deprecated.zeek
new file mode 100644
index 0000000000..70f91ff092
--- /dev/null
+++ b/testing/btest/cluster/websocket/one-ipv6-deprecated.zeek
@@ -0,0 +1,85 @@
+# @TEST-DOC: Use listen_host to listen on an IPv6 address, otherwise same as one-ipv6.zeek
+#
+# @TEST-REQUIRES: have-zeromq
+# @TEST-REQUIRES: python3 -c 'import websockets.sync'
+# @TEST-REQUIRES: can-listen-tcp 6 ::1
+#
+# @TEST-GROUP: cluster-zeromq
+#
+# @TEST-PORT: XPUB_PORT
+# @TEST-PORT: XSUB_PORT
+# @TEST-PORT: LOG_PULL_PORT
+# @TEST-PORT: WEBSOCKET_PORT
+#
+# @TEST-EXEC: cp $FILES/zeromq/cluster-layout-simple.zeek cluster-layout.zeek
+# @TEST-EXEC: cp $FILES/zeromq/test-bootstrap.zeek zeromq-test-bootstrap.zeek
+# @TEST-EXEC: cp $FILES/ws/wstest.py .
+#
+# @TEST-EXEC: zeek -b --parse-only manager.zeek
+# @TEST-EXEC: python3 -m py_compile client.py
+#
+# @TEST-EXEC: btest-bg-run manager "ZEEKPATH=$ZEEKPATH:.. && CLUSTER_NODE=manager zeek -b ../manager.zeek >out"
+# @TEST-EXEC: btest-bg-run client "python3 ../client.py >out"
+#
+# @TEST-EXEC: btest-bg-wait 30
+# @TEST-EXEC: btest-diff ./manager/out
+# @TEST-EXEC: btest-diff ./manager/.stderr
+# @TEST-EXEC: btest-diff ./client/out
+# @TEST-EXEC: btest-diff ./client/.stderr
+
+# @TEST-START-FILE manager.zeek
+@load ./zeromq-test-bootstrap
+redef exit_only_after_terminate = T;
+
+global ping_count = 0;
+
+global ping: event(msg: string, c: count) &is_used;
+global pong: event(msg: string, c: count) &is_used;
+
+event zeek_init()
+	{
+	Cluster::subscribe("/test/pings/");
+	Cluster::listen_websocket([$listen_host="::1", $listen_port=to_port(getenv("WEBSOCKET_PORT"))]);
+	}
+
+event ping(msg: string, n: count) &is_used
+	{
+	++ping_count;
+	print fmt("got ping: %s, %s", msg, n);
+	local e = Cluster::make_event(pong, "my-message", ping_count);
+	Cluster::publish("/test/pings", e);
+	}
+
+event Cluster::websocket_client_added(info: Cluster::EndpointInfo, subscriptions: string_vec)
+	{
+	print "Cluster::websocket_client_added", subscriptions;
+	}
+
+event Cluster::websocket_client_lost(info: Cluster::EndpointInfo, code: count, reason: string)
+	{
+	print "Cluster::websocket_client_lost";
+	terminate();
+	}
+# @TEST-END-FILE
+
+
+# @TEST-START-FILE client.py
+# @TEST-START-FILE client.py
+import wstest
+
+def run(ws_url):
+    with wstest.connect("ws1", ws_url) as tc:
+        print("Connected")
+        tc.hello_v1(["/test/pings"])
+
+        for i in range(5):
+            print("Sending ping", i)
+            tc.send_json(wstest.build_event_v1("/test/pings/", "ping", [f"ping {i}", i]))
+            pong = tc.recv_json()
+            assert pong["@data-type"] == "vector"
+            ev = pong["data"][2]["data"]
+            print("topic", pong["topic"], "event name", ev[0]["data"], "args", ev[1]["data"])
+
+if __name__ == "__main__":
+    wstest.main(run, wstest.WS6_URL_V1)
+# @TEST-END-FILE
diff --git a/testing/btest/cluster/websocket/one-ipv6.zeek b/testing/btest/cluster/websocket/one-ipv6.zeek
new file mode 100644
index 0000000000..9e50244e7a
--- /dev/null
+++ b/testing/btest/cluster/websocket/one-ipv6.zeek
@@ -0,0 +1,85 @@
+# @TEST-DOC: Make a WebSocket server listen on IPv6 ::1.
+#
+# @TEST-REQUIRES: have-zeromq
+# @TEST-REQUIRES: python3 -c 'import websockets.sync'
+# @TEST-REQUIRES: can-listen-tcp 6 ::1
+#
+# @TEST-GROUP: cluster-zeromq
+#
+# @TEST-PORT: XPUB_PORT
+# @TEST-PORT: XSUB_PORT
+# @TEST-PORT: LOG_PULL_PORT
+# @TEST-PORT: WEBSOCKET_PORT
+#
+# @TEST-EXEC: cp $FILES/zeromq/cluster-layout-simple.zeek cluster-layout.zeek
+# @TEST-EXEC: cp $FILES/zeromq/test-bootstrap.zeek zeromq-test-bootstrap.zeek
+# @TEST-EXEC: cp $FILES/ws/wstest.py .
+#
+# @TEST-EXEC: zeek -b --parse-only manager.zeek
+# @TEST-EXEC: python3 -m py_compile client.py
+#
+# @TEST-EXEC: btest-bg-run manager "ZEEKPATH=$ZEEKPATH:.. && CLUSTER_NODE=manager zeek -b ../manager.zeek >out"
+# @TEST-EXEC: btest-bg-run client "python3 ../client.py >out"
+#
+# @TEST-EXEC: btest-bg-wait 30
+# @TEST-EXEC: btest-diff ./manager/out
+# @TEST-EXEC: btest-diff ./manager/.stderr
+# @TEST-EXEC: btest-diff ./client/out
+# @TEST-EXEC: btest-diff ./client/.stderr
+
+# @TEST-START-FILE manager.zeek
+@load ./zeromq-test-bootstrap
+redef exit_only_after_terminate = T;
+
+global ping_count = 0;
+
+global ping: event(msg: string, c: count) &is_used;
+global pong: event(msg: string, c: count) &is_used;
+
+event zeek_init()
+	{
+	Cluster::subscribe("/test/pings/");
+	Cluster::listen_websocket([$listen_addr=[::1], $listen_port=to_port(getenv("WEBSOCKET_PORT"))]);
+	}
+
+event ping(msg: string, n: count) &is_used
+	{
+	++ping_count;
+	print fmt("got ping: %s, %s", msg, n);
+	local e = Cluster::make_event(pong, "my-message", ping_count);
+	Cluster::publish("/test/pings", e);
+	}
+
+event Cluster::websocket_client_added(info: Cluster::EndpointInfo, subscriptions: string_vec)
+	{
+	print "Cluster::websocket_client_added", subscriptions;
+	}
+
+event Cluster::websocket_client_lost(info: Cluster::EndpointInfo, code: count, reason: string)
+	{
+	print "Cluster::websocket_client_lost";
+	terminate();
+	}
+# @TEST-END-FILE
+
+
+# @TEST-START-FILE client.py
+# @TEST-START-FILE client.py
+import wstest
+
+def run(ws_url):
+    with wstest.connect("ws1", ws_url) as tc:
+        print("Connected")
+        tc.hello_v1(["/test/pings"])
+
+        for i in range(5):
+            print("Sending ping", i)
+            tc.send_json(wstest.build_event_v1("/test/pings/", "ping", [f"ping {i}", i]))
+            pong = tc.recv_json()
+            assert pong["@data-type"] == "vector"
+            ev = pong["data"][2]["data"]
+            print("topic", pong["topic"], "event name", ev[0]["data"], "args", ev[1]["data"])
+
+if __name__ == "__main__":
+    wstest.main(run, wstest.WS6_URL_V1)
+# @TEST-END-FILE
diff --git a/testing/btest/cluster/websocket/one-pipelining.zeek b/testing/btest/cluster/websocket/one-pipelining.zeek
index 0f43142280..6f42c4a297 100644
--- a/testing/btest/cluster/websocket/one-pipelining.zeek
+++ b/testing/btest/cluster/websocket/one-pipelining.zeek
@@ -37,7 +37,7 @@ global pong: event(msg: string, c: count) &is_used;
 event zeek_init()
 	{
 	Cluster::subscribe("/zeek/event/my_topic");
-	Cluster::listen_websocket([$listen_host="127.0.0.1", $listen_port=to_port(getenv("WEBSOCKET_PORT"))]);
+	Cluster::listen_websocket([$listen_addr=127.0.0.1, $listen_port=to_port(getenv("WEBSOCKET_PORT"))]);
 	}
 
 event ping(msg: string, n: count) &is_used
diff --git a/testing/btest/cluster/websocket/one.zeek b/testing/btest/cluster/websocket/one.zeek
index bcd6b7775e..a92e7e5e44 100644
--- a/testing/btest/cluster/websocket/one.zeek
+++ b/testing/btest/cluster/websocket/one.zeek
@@ -37,7 +37,7 @@ global pong: event(msg: string, c: count) &is_used;
 event zeek_init()
 	{
 	Cluster::subscribe("/zeek/event/my_topic");
-	Cluster::listen_websocket([$listen_host="127.0.0.1", $listen_port=to_port(getenv("WEBSOCKET_PORT"))]);
+	Cluster::listen_websocket([$listen_addr=127.0.0.1, $listen_port=to_port(getenv("WEBSOCKET_PORT"))]);
 	}
 
 event ping(msg: string, n: count) &is_used
diff --git a/testing/btest/cluster/websocket/ping-timeout.zeek b/testing/btest/cluster/websocket/ping-timeout.zeek
index f0347b1a3a..47c25606f6 100644
--- a/testing/btest/cluster/websocket/ping-timeout.zeek
+++ b/testing/btest/cluster/websocket/ping-timeout.zeek
@@ -39,7 +39,7 @@ event Cluster::websocket_client_lost(info: Cluster::EndpointInfo, code: count, r
 
 event zeek_init()
 	{
-	Cluster::listen_websocket([$listen_host="127.0.0.1", $listen_port=to_port(getenv("WEBSOCKET_PORT")), $ping_interval=1sec]);
+	Cluster::listen_websocket([$listen_addr=127.0.0.1, $listen_port=to_port(getenv("WEBSOCKET_PORT")), $ping_interval=1sec]);
 	Cluster::subscribe("/test/pings/");
 	}
 # @TEST-END-FILE
diff --git a/testing/btest/cluster/websocket/terminate-while-queuing.zeek b/testing/btest/cluster/websocket/terminate-while-queuing.zeek
index 006fa55dc8..787f02671a 100644
--- a/testing/btest/cluster/websocket/terminate-while-queuing.zeek
+++ b/testing/btest/cluster/websocket/terminate-while-queuing.zeek
@@ -53,7 +53,7 @@ event Cluster::websocket_client_lost(info: Cluster::EndpointInfo, code: count, r
 
 event zeek_init()
 	{
-	Cluster::listen_websocket([$listen_host="127.0.0.1", $listen_port=to_port(getenv("WEBSOCKET_PORT"))]);
+	Cluster::listen_websocket([$listen_addr=127.0.0.1, $listen_port=to_port(getenv("WEBSOCKET_PORT"))]);
 	Cluster::subscribe("/test/pings/");
 	}
 # @TEST-END-FILE
diff --git a/testing/btest/cluster/websocket/three.zeek b/testing/btest/cluster/websocket/three.zeek
index 3bf980cc8e..29938b45ce 100644
--- a/testing/btest/cluster/websocket/three.zeek
+++ b/testing/btest/cluster/websocket/three.zeek
@@ -71,7 +71,7 @@ event Cluster::Backend::ZeroMQ::subscription(topic: string)
 
 event zeek_init()
 	{
-	Cluster::listen_websocket([$listen_host="127.0.0.1", $listen_port=to_port(getenv("WEBSOCKET_PORT"))]);
+	Cluster::listen_websocket([$listen_addr=127.0.0.1, $listen_port=to_port(getenv("WEBSOCKET_PORT"))]);
 	Cluster::subscribe("/test/manager");
 	}
 # @TEST-END-FILE
diff --git a/testing/btest/cluster/websocket/tls-usage-error.zeek b/testing/btest/cluster/websocket/tls-usage-error.zeek
index d6357324dd..1b1329e3a4 100644
--- a/testing/btest/cluster/websocket/tls-usage-error.zeek
+++ b/testing/btest/cluster/websocket/tls-usage-error.zeek
@@ -14,6 +14,6 @@ event zeek_init()
 		$key_file="../localhost.key",
 	);
 
-	assert ! Cluster::listen_websocket([$listen_host="127.0.0.1", $listen_port=1234/tcp, $tls_options=tls_options_no_key]);
-	assert ! Cluster::listen_websocket([$listen_host="127.0.0.1", $listen_port=1234/tcp, $tls_options=tls_options_no_cert]);
+	assert ! Cluster::listen_websocket([$listen_addr=127.0.0.1, $listen_port=1234/tcp, $tls_options=tls_options_no_key]);
+	assert ! Cluster::listen_websocket([$listen_addr=127.0.0.1, $listen_port=1234/tcp, $tls_options=tls_options_no_cert]);
 	}
diff --git a/testing/btest/cluster/websocket/tls.zeek b/testing/btest/cluster/websocket/tls.zeek
index bd816c5328..235102428f 100644
--- a/testing/btest/cluster/websocket/tls.zeek
+++ b/testing/btest/cluster/websocket/tls.zeek
@@ -46,7 +46,7 @@ event zeek_init()
 	);
 
 	local ws_server_options = Cluster::WebSocketServerOptions(
-		$listen_host="127.0.0.1",
+		$listen_addr=127.0.0.1,
 		$listen_port=to_port(getenv("WEBSOCKET_PORT")),
 		$tls_options=tls_options,
 	);
diff --git a/testing/btest/cluster/websocket/two-pipelining.zeek b/testing/btest/cluster/websocket/two-pipelining.zeek
index fbf51da293..63a57c5280 100644
--- a/testing/btest/cluster/websocket/two-pipelining.zeek
+++ b/testing/btest/cluster/websocket/two-pipelining.zeek
@@ -103,7 +103,7 @@ event Cluster::Backend::ZeroMQ::subscription(topic: string)
 
 event zeek_init()
 	{
-	Cluster::listen_websocket([$listen_host="127.0.0.1", $listen_port=to_port(getenv("WEBSOCKET_PORT"))]);
+	Cluster::listen_websocket([$listen_addr=127.0.0.1, $listen_port=to_port(getenv("WEBSOCKET_PORT"))]);
 	Cluster::subscribe("/test/manager");
 	}
 # @TEST-END-FILE
diff --git a/testing/btest/cluster/websocket/zeromq/manager-worker-ping-pong.zeek b/testing/btest/cluster/websocket/zeromq/manager-worker-ping-pong.zeek
index b9f19948ef..a27d7f44fd 100644
--- a/testing/btest/cluster/websocket/zeromq/manager-worker-ping-pong.zeek
+++ b/testing/btest/cluster/websocket/zeromq/manager-worker-ping-pong.zeek
@@ -79,7 +79,7 @@ event Cluster::node_up(name: string, id: string)
 	# Delay listening on WebSocket clients until worker-1 is around.
 	if ( name == "worker-1" )
 		Cluster::listen_websocket([
-			$listen_host="127.0.0.1",
+			$listen_addr=127.0.0.1,
 			$listen_port=to_port(getenv("WEBSOCKET_PORT"))
 		]);
 	}
diff --git a/testing/btest/cluster/websocket/zeromq/no-subscriptions.zeek b/testing/btest/cluster/websocket/zeromq/no-subscriptions.zeek
index 305b0919eb..073056fb8f 100644
--- a/testing/btest/cluster/websocket/zeromq/no-subscriptions.zeek
+++ b/testing/btest/cluster/websocket/zeromq/no-subscriptions.zeek
@@ -33,7 +33,7 @@ redef exit_only_after_terminate = T;
 event zeek_init()
 	{
 	Cluster::subscribe("/test/pings");
-	Cluster::listen_websocket([$listen_host="127.0.0.1", $listen_port=to_port(getenv("WEBSOCKET_PORT"))]);
+	Cluster::listen_websocket([$listen_addr=127.0.0.1, $listen_port=to_port(getenv("WEBSOCKET_PORT"))]);
 	}
 
 global ping_count = 0;
diff --git a/testing/btest/cluster/websocket/zeromq/oneshot.zeek b/testing/btest/cluster/websocket/zeromq/oneshot.zeek
index 19f9f12720..e7e76521af 100644
--- a/testing/btest/cluster/websocket/zeromq/oneshot.zeek
+++ b/testing/btest/cluster/websocket/zeromq/oneshot.zeek
@@ -38,7 +38,7 @@ global ping: event(msg: string, c: count) &is_used;
 event zeek_init()
 	{
 	Cluster::subscribe("/test/pings");
-	Cluster::listen_websocket([$listen_host="127.0.0.1", $listen_port=to_port(getenv("WEBSOCKET_PORT"))]);
+	Cluster::listen_websocket([$listen_addr=127.0.0.1, $listen_port=to_port(getenv("WEBSOCKET_PORT"))]);
 	}
 
 event ping(msg: string, n: count) &is_used
diff --git a/testing/scripts/can-listen-tcp b/testing/scripts/can-listen-tcp
new file mode 100755
index 0000000000..7522daaed8
--- /dev/null
+++ b/testing/scripts/can-listen-tcp
@@ -0,0 +1,41 @@
+#!/usr/bin/env python3
+#
+# Try binding on the given family with addr and a port of 0 so that an
+# ephemeral port is allocated. This can be used to guard IPv6 tests.
+
+import socket
+import sys
+
+
+def usage():
+    print(f"Usage: {sys.argv[0]} 4|6 <addr>", file=sys.stderr)
+    sys.exit(1)
+
+
+if len(sys.argv) != 3:
+    usage()
+
+family = 0
+
+if sys.argv[1] == "4":
+    family = socket.AF_INET
+elif sys.argv[1] == "6":
+    family = socket.AF_INET6
+else:
+    usage()
+
+addr = sys.argv[2]
+port = 0
+
+s = socket.socket(family)
+
+try:
+    s.bind((addr, port))
+except Exception as e:
+    print(f"cannot listen on {addr}:{port} ({e!r})")
+    sys.exit(1)
+finally:
+    try:
+        s.close()
+    except:
+        pass