how to accept self-signed certificates for JNDI/LDAP connections?

According to the JNDI documentation it seems possible to set a custom SSLSocketFactory

http://download.oracle.com/javase/1.5.0/docs/guide/jndi/jndi-ldap-gl.html#socket

public class MySSLSocketFactory extends SocketFactory {
    private static final AtomicReference<MySSLSocketFactory> defaultFactory = new AtomicReference<>();

    private SSLSocketFactory sf;

    public MySSLSocketFactory() {
        KeyStore keyStore = ... /* Get a keystore containing the self-signed certificate) */
        TrustManagerFactory tmf = TrustManagerFactory.getInstance();
        tmf.init(keyStore);
        SSLContext ctx = SSLContext.getInstance("TLS");
        ctx.init(null, tmf.getTrustManagers(), null);
        sf = ctx.getSocketFactory();
    }

    public static SocketFactory getDefault() {
        final MySSLSocketFactory value = defaultFactory.get();
        if (value == null) {
            defaultFactory.compareAndSet(null, new MySSLSocketFactory());
            return defaultFactory.get();
        }
        return value;
    }

    @Override
    public Socket createSocket(final String s, final int i) throws IOException {
        return sf.createSocket(s, i);
    }

    @Override
    public Socket createSocket(final String s, final int i, final InetAddress inetAddress, final int i1) throws IOException {
        return sf.createSocket(s, i, inetAddress, i1);
    }

    @Override
    public Socket createSocket(final InetAddress inetAddress, final int i) throws IOException {
        return sf.createSocket(inetAddress, i);
    }

    @Override
    public Socket createSocket(final InetAddress inetAddress, final int i, final InetAddress inetAddress1, final int i1) throws IOException {
        return sf.createSocket(inetAddress, i, inetAddress1, i1);
    }
}

Configure the environment to use this socket factory

env.put("java.naming.ldap.factory.socket", "com.example.MySSLSocketFactory");

No code required. Just add the certificate to the test client truststores.

Don't write extra code for this. It is insecure, and you run a major risk of the code leaking into production. You really don't want that.

You could accept any certificate when you override the Trustmanager:

DummyTrustmanager.java

public class DummyTrustmanager implements X509TrustManager {
    public void checkClientTrusted(X509Certificate[] xcs, String string) throws CertificateException {
        // do nothing
    }

    public void checkServerTrusted(X509Certificate[] xcs, String string) throws CertificateException {
        // do nothing
    }

    public X509Certificate[] getAcceptedIssuers() {
        return new java.security.cert.X509Certificate[0];
    }
}

MySSLSocketFactory.java

public class MySSLSocketFactory extends SSLSocketFactory {
    private SSLSocketFactory socketFactory;

    public MySSLSocketFactory() {
        try {
            SSLContext ctx = SSLContext.getInstance("TLS");
            ctx.init(null, new TrustManager[] { new DummyTrustmanager() }, new SecureRandom());
            socketFactory = ctx.getSocketFactory();
        } catch (Exception ex) {
            ex.printStackTrace(System.err);
            /* handle exception */
        }
    }

    public static SocketFactory getDefault() {
        return new MySSLSocketFactory();
    }

    @Override
    public String[] getDefaultCipherSuites() {
        return socketFactory.getDefaultCipherSuites();
    }

    @Override
    public String[] getSupportedCipherSuites() {
        return socketFactory.getSupportedCipherSuites();
    }

    @Override
    public Socket createSocket(Socket socket, String string, int i, boolean bln) throws IOException {
        return socketFactory.createSocket(socket, string, i, bln);
    }

    @Override
    public Socket createSocket(String string, int i) throws IOException, UnknownHostException {
        return socketFactory.createSocket(string, i);
    }

    @Override
    public Socket createSocket(String string, int i, InetAddress ia, int i1) throws IOException, UnknownHostException {
        return socketFactory.createSocket(string, i, ia, i1);
    }

    @Override
    public Socket createSocket(InetAddress ia, int i) throws IOException {
        return socketFactory.createSocket(ia, i);
    }

    @Override
    public Socket createSocket(InetAddress ia, int i, InetAddress ia1, int i1) throws IOException {
        return socketFactory.createSocket(ia, i, ia1, i1);
    }

    @Override
    public Socket createSocket() throws IOException {
        return socketFactory.createSocket();
    }
}

Main.java

public class Main {
    public static void main(String[] args) throws NamingException {
        Hashtable env = new Hashtable(11);
        env.put(Context.INITIAL_CONTEXT_FACTORY, "com.sun.jndi.ldap.LdapCtxFactory");
        env.put(Context.PROVIDER_URL, "ldaps://ldapserver:636/");
        env.put(Context.SECURITY_PROTOCOL, "ssl");
        env.put(Context.SECURITY_AUTHENTICATION, "simple");
        env.put(Context.SECURITY_PRINCIPAL, "myUser");
        env.put(Context.SECURITY_CREDENTIALS, "myPassword");
        env.put("java.naming.ldap.factory.socket", "ldapsecure.MySSLSocketFactory");
        LdapContext ctx = new InitialLdapContext(env, null);
    }
}