diff --git a/tools/testing/selftests/net/tcp_ao/Makefile b/tools/testing/selftests/net/tcp_ao/Makefile
index a001dc2aed4e..da44966f3687 100644
--- a/tools/testing/selftests/net/tcp_ao/Makefile
+++ b/tools/testing/selftests/net/tcp_ao/Makefile
@@ -1,6 +1,6 @@
 # SPDX-License-Identifier: GPL-2.0
 TEST_BOTH_AF := connect icmps-discard icmps-accept connect-deny \
-		setsockopt-closed
+		setsockopt-closed unsigned-md5
 
 TEST_IPV4_PROGS := $(TEST_BOTH_AF:%=%_ipv4)
 TEST_IPV6_PROGS := $(TEST_BOTH_AF:%=%_ipv6)
diff --git a/tools/testing/selftests/net/tcp_ao/unsigned-md5.c b/tools/testing/selftests/net/tcp_ao/unsigned-md5.c
new file mode 100644
index 000000000000..1fd24c010588
--- /dev/null
+++ b/tools/testing/selftests/net/tcp_ao/unsigned-md5.c
@@ -0,0 +1,524 @@
+// SPDX-License-Identifier: GPL-2.0
+/* Author: Dmitry Safonov <dima@arista.com> */
+#include <inttypes.h>
+#include "aolib.h"
+#include "../../../../include/linux/bits.h"
+
+typedef uint8_t fault_t;
+#define F_TIMEOUT	1
+#define F_KEYREJECT	2
+#define F_PREINSTALL	3
+#define F_POSTINSTALL	4
+
+#define fault(type)	(inj == type)
+
+static const char *md5_password = "Some evil genius, enemy to mankind, must have been the first contriver.";
+static const char *ao_password = "In this hour, I do not believe that any darkness will endure.";
+
+static union tcp_addr client2;
+static union tcp_addr client3;
+
+static int test_set_md5(int sk, const union tcp_addr in_addr, uint8_t prefix)
+{
+	size_t pwd_len = strlen(md5_password);
+	struct tcp_md5sig md5sig = {};
+#ifdef IPV6_TEST
+	struct sockaddr_in6 addr = {
+		.sin6_family	= AF_INET6,
+		.sin6_port	= 0,
+		.sin6_addr	= in_addr.a6,
+	};
+#else
+	struct sockaddr_in addr = {
+		.sin_family	= AF_INET,
+		.sin_port	= 0,
+		.sin_addr	= in_addr.a4,
+	};
+#endif
+
+	if (prefix > DEFAULT_TEST_PREFIX)
+		prefix = DEFAULT_TEST_PREFIX;
+
+	md5sig.tcpm_keylen = pwd_len;
+	memcpy(md5sig.tcpm_key, md5_password, pwd_len);
+	md5sig.tcpm_flags = TCP_MD5SIG_FLAG_PREFIX;
+	md5sig.tcpm_prefixlen = prefix;
+	memcpy(&md5sig.tcpm_addr, &addr, sizeof(addr));
+
+	return setsockopt(sk, IPPROTO_TCP, TCP_MD5SIG_EXT,
+			  &md5sig, sizeof(md5sig));
+}
+
+static bool tcp_md5_enabled = true;
+static void check_tcp_md5_support(void)
+{
+	int sk;
+	union tcp_addr addr_any = {};
+
+	sk = socket(test_family, SOCK_STREAM, IPPROTO_TCP);
+	if (sk < 0)
+		test_error("socket()");
+
+	if (test_set_md5(sk, addr_any, 0)) {
+		if (errno == ENOPROTOOPT)
+			tcp_md5_enabled = false;
+		else
+			test_error("setsockopt(TCP_MD5SIG_EXT)");
+	}
+	close(sk);
+}
+
+static void try_accept(const char *tst_name, unsigned int port,
+		       union tcp_addr *md5_addr, uint8_t md5_prefix,
+		       union tcp_addr *ao_addr, uint8_t ao_prefix,
+		       uint8_t sndid, uint8_t rcvid, const char *cnt_name,
+		       bool needs_md5, fault_t inj)
+{
+	uint64_t before_cnt, after_cnt;
+	int lsk, err, sk = 0;
+	time_t timeout;
+
+	if (needs_md5 && !tcp_md5_enabled) {
+		test_skip("%s: setsockopt(TCP_MD5SIG_EXT) is not supported", tst_name);
+		return;
+	}
+
+	lsk = test_listen_socket(this_ip_addr, port, 1);
+
+	if (md5_addr && test_set_md5(lsk, *md5_addr, md5_prefix))
+		test_error("setsockopt(TCP_MD5SIG_EXT)");
+
+	if (ao_addr && test_set_ao(lsk, ao_password, 0, *ao_addr,
+				   ao_prefix, sndid, rcvid))
+		test_error("setsockopt(TCP_AO)");
+
+	if (cnt_name)
+		before_cnt = netstat_get_one(cnt_name, NULL);
+
+	synchronize_threads(); /* preparations done */
+
+	timeout = fault(F_TIMEOUT) ? TEST_RETRANSMIT_SEC : TEST_TIMEOUT_SEC;
+	err = test_wait_fd(lsk, timeout, 0);
+	if (err < 0)
+		test_error("test_wait_fd()");
+	else if (!err) {
+		if (!fault(F_TIMEOUT))
+			test_fail("timeouted for accept()");
+	} else {
+		if (fault(F_TIMEOUT))
+			test_fail("ready to accept");
+
+		sk = accept(lsk, NULL, NULL);
+		if (sk < 0) {
+			test_error("accept()");
+		} else {
+			if (fault(F_TIMEOUT))
+				test_fail("%s: accepted", tst_name);
+		}
+	}
+
+	close(lsk);
+
+	if (!cnt_name)
+		goto out;
+
+	after_cnt = netstat_get_one(cnt_name, NULL);
+
+	if (after_cnt <= before_cnt) {
+		test_fail("%s: %s counter did not increase: %zu <= %zu",
+				tst_name, cnt_name, after_cnt, before_cnt);
+	} else {
+		test_ok("%s: counter %s increased %zu => %zu",
+			tst_name, cnt_name, before_cnt, after_cnt);
+	}
+
+out:
+	synchronize_threads(); /* close() */
+	if (sk > 0)
+		close(sk);
+}
+
+static void server_add_routes(void)
+{
+	int family = TEST_FAMILY;
+
+	check_tcp_md5_support();
+	synchronize_threads(); /* client_add_ips() */
+
+	if (ip_route_add(veth_name, family, this_ip_addr, client2))
+		test_error("Failed to add route");
+	if (ip_route_add(veth_name, family, this_ip_addr, client3))
+		test_error("Failed to add route");
+}
+
+static void server_add_fail_tests(unsigned int *port)
+{
+	union tcp_addr addr_any = {};
+
+	try_accept("TCP-AO established: add TCP-MD5 key", (*port)++, NULL, 0,
+		   &addr_any, 0, 100, 100, "TCPAOGood", true, 0);
+	try_accept("TCP-MD5 established: add TCP-AO key", (*port)++, &addr_any, 0,
+		   NULL, 0, 0, 0, NULL, true, 0);
+	try_accept("non-signed established: add TCP-AO key", (*port)++, NULL, 0,
+		   NULL, 0, 0, 0, "CurrEstab", false, 0);
+}
+
+static void *server_fn(void *arg)
+{
+	unsigned int port = test_server_port;
+	union tcp_addr addr_any = {};
+
+	server_add_routes();
+
+	try_accept("AO server (INADDR_ANY): AO client", port++, NULL, 0,
+		   &addr_any, 0, 100, 100, "TCPAOGood", false, 0);
+	try_accept("AO server (INADDR_ANY): MD5 client", port++, NULL, 0,
+		   &addr_any, 0, 100, 100, "TCPMD5Unexpected", true, F_TIMEOUT);
+	try_accept("AO server (INADDR_ANY): no sign client", port++, NULL, 0,
+		   &addr_any, 0, 100, 100, "TCPAORequired", false, F_TIMEOUT);
+
+	try_accept("MD5 server (INADDR_ANY): AO client", port++, &addr_any, 0,
+		   NULL, 0, 0, 0, "TCPAOKeyNotFound", true, F_TIMEOUT);
+	try_accept("MD5 server (INADDR_ANY): MD5 client", port++, &addr_any, 0,
+		   NULL, 0, 0, 0, NULL, true, 0);
+	try_accept("MD5 server (INADDR_ANY): no sign client", port++, &addr_any, 0,
+		   NULL, 0, 0, 0, "TCPMD5NotFound", true, F_TIMEOUT);
+
+	try_accept("no sign server: AO client", port++, NULL, 0,
+		   NULL, 0, 0, 0, "TCPAOKeyNotFound", false, F_TIMEOUT);
+	try_accept("no sign server: MD5 client", port++, NULL, 0,
+		   NULL, 0, 0, 0, "TCPMD5Unexpected", true, F_TIMEOUT);
+	try_accept("no sign server: no sign client", port++, NULL, 0,
+		   NULL, 0, 0, 0, "CurrEstab", false, 0);
+
+	try_accept("AO+MD5 server: AO client (matching)", port++,
+		&this_ip_dest, TEST_PREFIX, &client2, TEST_PREFIX,
+		100, 100, "TCPAOGood", true, 0);
+	try_accept("AO+MD5 server: AO client (misconfig, matching MD5)", port++,
+		&this_ip_dest, TEST_PREFIX, &client2, TEST_PREFIX,
+		100, 100, "TCPAOKeyNotFound", true, F_TIMEOUT);
+	try_accept("AO+MD5 server: AO client (misconfig, non-matching)", port++,
+		&this_ip_dest, TEST_PREFIX, &client2, TEST_PREFIX,
+		100, 100, "TCPAOKeyNotFound", true, F_TIMEOUT);
+	try_accept("AO+MD5 server: MD5 client (matching)", port++,
+		&this_ip_dest, TEST_PREFIX, &client2, TEST_PREFIX,
+		100, 100, NULL, true, 0);
+	try_accept("AO+MD5 server: MD5 client (misconfig, matching AO)", port++,
+		&this_ip_dest, TEST_PREFIX, &client2, TEST_PREFIX,
+		100, 100, "TCPMD5Unexpected", true, F_TIMEOUT);
+	try_accept("AO+MD5 server: MD5 client (misconfig, non-matching)", port++,
+		&this_ip_dest, TEST_PREFIX, &client2, TEST_PREFIX,
+		100, 100, "TCPMD5Unexpected", true, F_TIMEOUT);
+	try_accept("AO+MD5 server: no sign client (unmatched)", port++,
+		&this_ip_dest, TEST_PREFIX, &client2, TEST_PREFIX,
+		100, 100, "CurrEstab", true, 0);
+	try_accept("AO+MD5 server: no sign client (misconfig, matching AO)",
+		port++, &this_ip_dest, TEST_PREFIX, &client2, TEST_PREFIX,
+		100, 100, "TCPAORequired", true, F_TIMEOUT);
+	try_accept("AO+MD5 server: no sign client (misconfig, matching MD5)",
+		port++, &this_ip_dest, TEST_PREFIX, &client2, TEST_PREFIX,
+		100, 100, "TCPMD5NotFound", true, F_TIMEOUT);
+
+	try_accept("AO+MD5 server: client with both [TCP-MD5] and TCP-AO keys",
+		port++, &this_ip_dest, TEST_PREFIX, &client2, TEST_PREFIX,
+		100, 100, NULL, true, F_TIMEOUT);
+	try_accept("AO+MD5 server: client with both TCP-MD5 and [TCP-AO] keys",
+		port++, &this_ip_dest, TEST_PREFIX, &client2, TEST_PREFIX,
+		100, 100, NULL, true, F_TIMEOUT);
+
+	server_add_fail_tests(&port);
+
+	/* client exits */
+	synchronize_threads();
+	return NULL;
+}
+
+static int client_bind(int sk, union tcp_addr bind_addr)
+{
+#ifdef IPV6_TEST
+	struct sockaddr_in6 addr = {
+		.sin6_family	= AF_INET6,
+		.sin6_port	= 0,
+		.sin6_addr	= bind_addr.a6,
+	};
+#else
+	struct sockaddr_in addr = {
+		.sin_family	= AF_INET,
+		.sin_port	= 0,
+		.sin_addr	= bind_addr.a4,
+	};
+#endif
+	return bind(sk, &addr, sizeof(addr));
+}
+
+static void try_connect(const char *tst_name, unsigned int port,
+		       union tcp_addr *md5_addr, uint8_t md5_prefix,
+		       union tcp_addr *ao_addr, uint8_t ao_prefix,
+		       uint8_t sndid, uint8_t rcvid, fault_t inj,
+		       bool needs_md5, union tcp_addr *bind_addr)
+{
+	time_t timeout;
+	int sk, ret;
+
+	if (needs_md5 && !tcp_md5_enabled) {
+		test_skip("%s: setsockopt(TCP_MD5SIG_EXT) is not supported", tst_name);
+		return;
+	}
+
+	sk = socket(test_family, SOCK_STREAM, IPPROTO_TCP);
+	if (sk < 0)
+		test_error("socket()");
+
+	if (bind_addr && client_bind(sk, *bind_addr))
+		test_error("bind()");
+
+	if (md5_addr && test_set_md5(sk, *md5_addr, md5_prefix))
+		test_error("setsockopt(TCP_MD5SIG_EXT)");
+
+	if (ao_addr && test_set_ao(sk, ao_password, 0, *ao_addr,
+				   ao_prefix, sndid, rcvid))
+		test_error("setsockopt(TCP_AO)");
+
+	synchronize_threads(); /* preparations done */
+
+	timeout = fault(F_TIMEOUT) ? TEST_RETRANSMIT_SEC : TEST_TIMEOUT_SEC;
+	ret = _test_connect_socket(sk, this_ip_dest, port, timeout);
+
+	if (ret < 0) {
+		if (fault(F_KEYREJECT) && ret == -EKEYREJECTED) {
+			test_ok("%s: connect() was prevented", tst_name);
+			goto out;
+		} else if (ret == -ECONNREFUSED &&
+				(fault(F_TIMEOUT) || fault(F_KEYREJECT))) {
+			test_ok("%s: refused to connect", tst_name);
+			goto out;
+		} else {
+			test_error("%s: connect() returned %d", tst_name, ret);
+		}
+	}
+
+	if (ret == 0) {
+		if (fault(F_TIMEOUT))
+			test_ok("%s", tst_name);
+		else
+			test_fail("%s: failed to connect()", tst_name);
+	} else {
+		if (fault(F_TIMEOUT) || fault(F_KEYREJECT))
+			test_fail("%s: connected", tst_name);
+		else
+			test_ok("%s: connected", tst_name);
+	}
+
+out:
+	synchronize_threads(); /* close() */
+	/* _test_connect_socket() cleans up on failure */
+	if (ret > 0)
+		close(sk);
+}
+
+#define PREINSTALL_MD5	BIT(1)
+#define POSTINSTALL_MD5	BIT(2)
+#define PREINSTALL_AO	BIT(3)
+#define POSTINSTALL_AO	BIT(4)
+
+static void try_to_add(const char *tst_name, unsigned int port,
+		       unsigned int strategy,
+		       union tcp_addr md5_addr, uint8_t md5_prefix,
+		       union tcp_addr ao_addr, uint8_t ao_prefix,
+		       uint8_t sndid, uint8_t rcvid,
+		       bool needs_md5, fault_t inj)
+{
+	time_t timeout;
+	int sk, ret;
+
+	if (needs_md5 && !tcp_md5_enabled) {
+		test_skip("%s: setsockopt(TCP_MD5SIG_EXT) is not supported", tst_name);
+		return;
+	}
+
+	sk = socket(test_family, SOCK_STREAM, IPPROTO_TCP);
+	if (sk < 0)
+		test_error("socket()");
+
+	if (client_bind(sk, this_ip_addr))
+		test_error("bind()");
+
+	if (strategy & PREINSTALL_MD5) {
+		if (test_set_md5(sk, md5_addr, md5_prefix))
+			test_error("setsockopt(TCP_MD5SIG_EXT)");
+	}
+
+	if (strategy & PREINSTALL_AO) {
+		if (test_set_ao(sk, ao_password, 0, ao_addr,
+				ao_prefix, sndid, rcvid)) {
+			if (fault(F_PREINSTALL)) {
+				test_ok("%s: prefailed as expected", tst_name);
+				goto out_no_sync;
+			} else {
+				test_error("setsockopt(TCP_AO)");
+			}
+		} else if (fault(F_PREINSTALL)) {
+			test_fail("%s: setsockopt()s were expected to fail", tst_name);
+			goto out_no_sync;
+		}
+	}
+
+	synchronize_threads(); /* preparations done */
+
+	timeout = fault(F_TIMEOUT) ? TEST_RETRANSMIT_SEC : TEST_TIMEOUT_SEC;
+	ret = _test_connect_socket(sk, this_ip_dest, port, timeout);
+
+	if (ret <= 0) {
+		test_error("%s: connect() returned %d", tst_name, ret);
+		goto out;
+	}
+
+	if (strategy & POSTINSTALL_MD5) {
+		if (test_set_md5(sk, md5_addr, md5_prefix)) {
+			if (fault(F_POSTINSTALL)) {
+				test_ok("%s: postfailed as expected", tst_name);
+				goto out;
+			} else {
+				test_error("setsockopt(TCP_MD5SIG_EXT)");
+			}
+		} else if (fault(F_POSTINSTALL)) {
+			test_fail("%s: post setsockopt() was expected to fail", tst_name);
+			goto out;
+		}
+	}
+
+	if (strategy & POSTINSTALL_AO) {
+		if (test_set_ao(sk, ao_password, 0, ao_addr,
+				ao_prefix, sndid, rcvid)) {
+			if (fault(F_POSTINSTALL)) {
+				test_ok("%s: postfailed as expected", tst_name);
+				goto out;
+			} else {
+				test_error("setsockopt(TCP_AO)");
+			}
+		} else if (fault(F_POSTINSTALL)) {
+			test_fail("%s: post setsockopt() was expected to fail", tst_name);
+			goto out;
+		}
+	}
+
+out:
+	synchronize_threads(); /* close() */
+out_no_sync:
+	/* _test_connect_socket() cleans up on failure */
+	if (ret > 0)
+		close(sk);
+}
+
+static void client_add_ip(union tcp_addr *client, const char *ip)
+{
+	int family = TEST_FAMILY;
+
+	if (inet_pton(family, ip, client) != 1)
+		test_error("Can't convert ip address %s", ip);
+
+	if (ip_addr_add(veth_name, family, *client, TEST_PREFIX))
+		test_error("Failed to add ip address");
+	if (ip_route_add(veth_name, family, *client, this_ip_dest))
+		test_error("Failed to add route");
+}
+
+static void client_add_ips(void)
+{
+	client_add_ip(&client2, __TEST_CLIENT_IP(2));
+	client_add_ip(&client3, __TEST_CLIENT_IP(3));
+	synchronize_threads(); /* server_add_routes() */
+}
+
+static void client_add_fail_tests(unsigned int *port)
+{
+	try_to_add("TCP-AO established: add TCP-MD5 key",
+		   (*port)++, POSTINSTALL_MD5 | PREINSTALL_AO,
+		   this_ip_dest, TEST_PREFIX, this_ip_dest, TEST_PREFIX,
+		   100, 100, true, F_POSTINSTALL);
+	try_to_add("TCP-MD5 established: add TCP-AO key",
+		   (*port)++, PREINSTALL_MD5 | POSTINSTALL_AO,
+		   this_ip_dest, TEST_PREFIX, this_ip_dest, TEST_PREFIX,
+		   100, 100, true, F_POSTINSTALL);
+	try_to_add("non-signed established: add TCP-AO key",
+		   (*port)++, POSTINSTALL_AO,
+		   this_ip_dest, TEST_PREFIX, this_ip_dest, TEST_PREFIX,
+		   100, 100, false, F_POSTINSTALL);
+
+	try_to_add("TCP-AO key intersects with TCP-MD5 key",
+		   (*port), PREINSTALL_MD5 | PREINSTALL_AO,
+		   this_ip_addr, TEST_PREFIX, this_ip_addr, TEST_PREFIX,
+		   100, 100, true, F_PREINSTALL);
+}
+
+static void *client_fn(void *arg)
+{
+	unsigned int port = test_server_port;
+	union tcp_addr addr_any = {};
+
+	client_add_ips();
+
+	try_connect("AO server (INADDR_ANY): AO client", port++, NULL, 0,
+		    &addr_any, 0, 100, 100, 0, false, &this_ip_addr);
+	try_connect("AO server (INADDR_ANY): MD5 client", port++, &addr_any, 0,
+		    NULL, 0, 100, 100, F_TIMEOUT, true, &this_ip_addr);
+	try_connect("AO server (INADDR_ANY): unsigned client", port++, NULL, 0,
+		    NULL, 0, 100, 100, F_TIMEOUT, false, &this_ip_addr);
+
+	try_connect("MD5 server (INADDR_ANY): AO client", port++, NULL, 0,
+		   &addr_any, 0, 100, 100, F_TIMEOUT, true, &this_ip_addr);
+	try_connect("MD5 server (INADDR_ANY): MD5 client", port++, &addr_any, 0,
+		   NULL, 0, 100, 100, 0, true, &this_ip_addr);
+	try_connect("MD5 server (INADDR_ANY): no sign client", port++, NULL, 0,
+		   NULL, 0, 100, 100, F_TIMEOUT, true, &this_ip_addr);
+
+	try_connect("no sign server: AO client", port++, NULL, 0,
+		   &addr_any, 0, 100, 100, F_TIMEOUT, false, &this_ip_addr);
+	try_connect("no sign server: MD5 client", port++, &addr_any, 0,
+		   NULL, 0, 100, 100, F_TIMEOUT, true, &this_ip_addr);
+	try_connect("no sign server: no sign client", port++, NULL, 0,
+		   NULL, 0, 100, 100, 0, false, &this_ip_addr);
+
+	try_connect("AO+MD5 server: AO client (matching)", port++, NULL, 0,
+		   &addr_any, 0, 100, 100, 0, true, &client2);
+	try_connect("AO+MD5 server: AO client (misconfig, matching MD5)",
+		   port++, NULL, 0, &addr_any, 0, 100, 100,
+		   F_TIMEOUT, true, &this_ip_addr);
+	try_connect("AO+MD5 server: AO client (misconfig, non-matching)",
+		   port++, NULL, 0, &addr_any, 0, 100, 100,
+		   F_TIMEOUT, true, &client3);
+	try_connect("AO+MD5 server: MD5 client (matching)", port++, &addr_any, 0,
+		   NULL, 0, 100, 100, 0, true, &this_ip_addr);
+	try_connect("AO+MD5 server: MD5 client (misconfig, matching AO)",
+		   port++, &addr_any, 0, NULL, 0, 100, 100, F_TIMEOUT,
+		   true, &client2);
+	try_connect("AO+MD5 server: MD5 client (misconfig, non-matching)",
+		   port++, &addr_any, 0, NULL, 0, 100, 100, F_TIMEOUT,
+		   true, &client3);
+	try_connect("AO+MD5 server: no sign client (unmatched)",
+		   port++, NULL, 0, NULL, 0, 100, 100, 0, true, &client3);
+	try_connect("AO+MD5 server: no sign client (misconfig, matching AO)",
+		   port++, NULL, 0, NULL, 0, 100, 100, F_TIMEOUT,
+		   true, &client2);
+	try_connect("AO+MD5 server: no sign client (misconfig, matching MD5)",
+		   port++, NULL, 0, NULL, 0, 100, 100, F_TIMEOUT,
+		   true, &this_ip_addr);
+
+	try_connect("AO+MD5 server: client with both [TCP-MD5] and TCP-AO keys",
+		   port++, &this_ip_addr, TEST_PREFIX,
+		   &client2, TEST_PREFIX, 100, 100, F_KEYREJECT,
+		   true, &this_ip_addr);
+	try_connect("AO+MD5 server: client with both TCP-MD5 and [TCP-AO] keys",
+		   port++, &this_ip_addr, TEST_PREFIX,
+		   &client2, TEST_PREFIX, 100, 100, F_KEYREJECT, true, &client2);
+
+	client_add_fail_tests(&port);
+
+	return NULL;
+}
+
+int main(int argc, char *argv[])
+{
+	test_init(42, server_fn, client_fn);
+	return 0;
+}
