[SSHD-1066] Support multiple local interfaces in PortForwarding

• Type: New Feature
• Status: Resolved
• Priority: Major
• Resolution: Fixed
• Affects Version/s: 2.5.1
• Fix Version/s: 2.6.0
• Assignee: Lyor Goldstein
• Reporter: Guillermo Grandes
• Created: 27/Aug/20 17:30
• Updated: 29/Jan/24 10:48
• Resolved: 29/Oct/20 17:30

Description

I'm trying to listen in same port on 2 IPs of same machine, multihomed, the equivalent in openssh is:

# ssh -L 127.0.0.2:8080:test.javastack.org:80 -L 127.0.0.3:8080:test.javastack.org:80 test-sshd@server -N
# sudo netstat -lntp | grep :8080
tcp  0 0  127.0.0.3:8080  0.0.0.0:*  LISTEN  2650/ssh
tcp  0 0  127.0.0.2:8080  0.0.0.0:*  LISTEN  2650/ssh

Sample code to reproduce the test case:

	public static final int DEFAULT_TIMEOUT = 10000;

	public static void test(final String username, final String password, final String host, final int port)
			throws IOException {
		boolean testLocal = true;
		try (SshClient client = SshClient.setUpDefaultClient()) {
			client.setServerKeyVerifier(AcceptAllServerKeyVerifier.INSTANCE);
			client.start();
			try {
				ConnectFuture connect = client.connect(username, host, port);
				connect.await(DEFAULT_TIMEOUT);
				ClientSession session = connect.getClientSession();
				session.addPasswordIdentity(password);
				session.auth().verify(DEFAULT_TIMEOUT);

				if (testLocal) {
					System.out.println("================== Local 1 ==================");
					ExplicitPortForwardingTracker localTracker1 = session.createLocalPortForwardingTracker(
							new SshdSocketAddress("127.0.0.2", 8080),
							new SshdSocketAddress("test.javastack.org", 80));
					sleep(1000);
					System.out.println("LocalPortForwarding: " //
							+ localTracker1.getLocalAddress() + " -> " //
							+ localTracker1.getRemoteAddress());
					SshdSocketAddress localSocketAddress1 = localTracker1.getLocalAddress();
					if (localSocketAddress1 != null) {
						Proxy proxy = new Proxy(Proxy.Type.HTTP,
								new InetSocketAddress(localSocketAddress1.getHostName(), //
										localSocketAddress1.getPort()));
						testRemoteURL(proxy, "http://test.javastack.org/");
					}
					System.out.println("================== Local 2 ==================");
					ExplicitPortForwardingTracker localTracker2 = session.createLocalPortForwardingTracker(
							new SshdSocketAddress("127.0.0.3", 8080),
							new SshdSocketAddress("test.javastack.org", 80));
					sleep(1000);
					System.out.println("LocalPortForwarding: " //
							+ localTracker2.getLocalAddress() + " -> " //
							+ localTracker2.getRemoteAddress());
					SshdSocketAddress localSocketAddress2 = localTracker2.getLocalAddress();
					if (localSocketAddress2 != null) {
						Proxy proxy = new Proxy(Proxy.Type.HTTP,
								new InetSocketAddress(localSocketAddress2.getHostName(), //
										localSocketAddress2.getPort()));
						testRemoteURL(proxy, "http://test.javastack.org/");
					}
				}
			} finally {
				client.stop();
			}
		}

	}

	private static final void sleep(final long t) {
		try {
			Thread.sleep(t);
		} catch (Exception ign) {
		}
	}

	private static final void testRemoteURL(final Proxy proxy, final String url) throws IOException {
		HttpURLConnection connection = (HttpURLConnection) new URL(url).openConnection(proxy);
		connection.setConnectTimeout(DEFAULT_TIMEOUT);
		connection.setReadTimeout(DEFAULT_TIMEOUT);
		System.out.println("Get URL: " + connection.getURL());
		try {
			BufferedReader in = new BufferedReader(new InputStreamReader(connection.getInputStream()));
			System.out.println("Response from server:");
			String inputLine;
			while ((inputLine = in.readLine()) != null) {
				System.out.println(inputLine);
			}
			in.close();
		} catch (Exception e) {
			System.out.println("Failed: " + e);
		}
	}

	public static void main(String[] args) throws Throwable {
		test("test-sshd", "secret", "server", 22);
		sleep(3000);
	}

Error received:

Exception in thread "main" java.io.IOException: Multiple local port forwarding addressing on port=8080: current=test.javastack.org:80, previous=test.javastack.org:80
	at org.apache.sshd.common.forward.DefaultForwardingFilter.startLocalPortForwarding(DefaultForwardingFilter.java:208)
	at org.apache.sshd.client.session.AbstractClientSession.startLocalPortForwarding(AbstractClientSession.java:374)
	at org.apache.sshd.client.session.ClientSession.createLocalPortForwardingTracker(ClientSession.java:316)
	at org.javastack.jentunnel.sandbox.SimpleBindingTest.test(SimpleBindingTest.java:52)

Result Expected:

================== Local 1 ==================
LocalPortForwarding: 127.0.0.2:8080 -> test.javastack.org:80
Get URL: http://test.javastack.org/
Response from server:
OK
================== Local 2 ==================
LocalPortForwarding: 127.0.0.3:8080 -> test.javastack.org:80
Get URL: http://test.javastack.org/
Response from server:
OK

• Note-1: The usage of loopback addresses (127.0.0.0/8) and same destination is to simplify/reproduce easily, don't care.
• Note-2: I don't checked if startRemotePortForwarding/startDynamicPortForwarding reproduce same issue as startLocalPortForwarding. But I suppose that yes.

Issue Links

• causes: SSHD-1269 TCP/IP remote port forwarding with wildcard IP addresses doesn't work with OpenSSH
• relates to: SSHD-1033 Unable to use DynamicPortForwarding + LocalPortForwarding
• links to: GitHub Pull Request #170