IPSecDemo.m

- (void)viewDidLoad
{
    [super viewDidLoad];

    // init VPN manager
    self.vpnManager = [NEVPNManager sharedManager];

    // load config from perference
    [_vpnManager loadFromPreferencesWithCompletionHandler:^(NSError *error) {

        if (error) {
            NSLog(@"Load config failed [%@]", error.localizedDescription);
            return;
        }
        
        if (_vpnManager.protocol) {
            // config exists
        }
        
        // config IPSec protocol        
        NEVPNProtocolIPSec *p = [[NEVPNProtocolIPSec alloc] init];
        p.username = @"[Your username]";
        p.serverAddress = @"[Your server address]";;

        // get password persistent reference from keychain
        p.passwordReference = [self searchKeychainCopyMatching:@"VPN_PASSWORD"];

        // PSK
        p.authenticationMethod = NEVPNIKEAuthenticationMethodSharedSecret;
        p.sharedSecretReference = [self searchKeychainCopyMatching:@"PSK"];
        
        /*
        // certificate
        p.identityData = [NSData dataWithContentsOfFile:[[NSBundle mainBundle] pathForResource:@"client" ofType:@"p12"]];
        p.identityDataPassword = @"[Your certificate import password]";
        */

        p.localIdentifier = @"[VPN local identifier]";
        p.remoteIdentifier = @"[VPN remote identifier]";
        
        p.useExtendedAuthentication = YES;
        p.disconnectOnSleep = NO;
        
        _vpnManager.protocol = p;
        _vpnManager.localizedDescription = @"IPSec Demo";

        [_vpnManager saveToPreferencesWithCompletionHandler:^(NSError *error) {
            NSLog(@"Save config failed [%@]", error.localizedDescription);
        }];
    }];
}

- (IBAction)startVPNConnection:(id)sender {
    //[[VodManager sharedManager] installVPNProfile];
    
    NSError *startError;
    [_vpnManager.connection startVPNTunnelAndReturnError:&startError];
    if (startError) {
        NSLog("Start VPN failed: [%@]", startError.localizedDescription);
    }
}

static NSString * const serviceName = @"im.zorro.ipsec_demo.vpn_config";

- (NSData *)searchKeychainCopyMatching:(NSString *)identifier {
    NSMutableDictionary *searchDictionary = [[NSMutableDictionary alloc] init];
        
    NSData *encodedIdentifier = [identifier dataUsingEncoding:NSUTF8StringEncoding];
    
    searchDictionary[(__bridge id)kSecClass] = (__bridge id)kSecClassGenericPassword;
    searchDictionary[(__bridge id)kSecAttrGeneric] = encodedIdentifier;
    searchDictionary[(__bridge id)kSecAttrAccount] = encodedIdentifier;
    searchDictionary[(__bridge id)kSecAttrService] = serviceName;

    searchDictionary[(__bridge id)kSecMatchLimit] = (__bridge id)kSecMatchLimitOne;
    searchDictionary[(__bridge id)kSecReturnPersistentRef] = @YES;
    
    CFTypeRef result = NULL;
    SecItemCopyMatching((__bridge CFDictionaryRef)searchDictionary, &result);
    
    return (__bridge_transfer NSData *)result;
}