Index: src/SSLSocket.m
==================================================================
--- src/SSLSocket.m
+++ src/SSLSocket.m
@@ -378,11 +378,13 @@
 		     block: (of_tcp_socket_async_connect_block_t)block
 {
 	[super asyncConnectToHost: host
 			     port: port
 		      runLoopMode: runLoopMode
-			    block: ^ (SSLSocket *sock, id exception) {
+			    block: ^ (OFTCPSocket *sock_, id exception) {
+		SSLSocket *sock = (SSLSocket *)sock_;
+
 		if (exception == nil) {
 			@try {
 				[sock SSL_startTLSWithExpectedHost: host
 							      port: port];
 			} @catch (id e) {
@@ -446,10 +448,20 @@
 - (size_t)lowlevelReadIntoBuffer: (void *)buffer
 			  length: (size_t)length
 {
 	ssize_t ret;
 
+	/*
+	 * There is no SSL session yet. However, it might be necessary to read
+	 * from and write to the socket before negotiating an SSL session: For
+	 * example, the socket might be connected to a SOCKS5 proxy and needs
+	 * to establish a SOCKS5 connection before negotiating an SSL session.
+	 */
+	if (_SSL == NULL)
+		return [super lowlevelReadIntoBuffer: buffer
+					      length: length];
+
 	if (length > INT_MAX)
 		@throw [OFOutOfRangeException exception];
 
 	if (_socket == INVALID_SOCKET)
 		@throw [OFNotOpenException exceptionWithObject: self];
@@ -477,10 +489,24 @@
 - (size_t)lowlevelWriteBuffer: (const void *)buffer
 		       length: (size_t)length
 {
 	int bytesWritten;
 
+	/*
+	 * There is no SSL session yet. However, it might be necessary to read
+	 * from and write to the socket before negotiating an SSL session: For
+	 * example, the socket might be connected to a SOCKS5 proxy and needs
+	 * to establish a SOCKS5 connection before negotiating an SSL session.
+	 *
+	 * TODO: Think of a way to make this safer, so that it's impossible to
+	 * forget to establish an SSL session and then send unencrypted data by
+	 * accident.
+	 */
+	if (_SSL == NULL)
+		return [super lowlevelWriteBuffer: buffer
+					   length: length];
+
 	if (_socket == INVALID_SOCKET)
 		@throw [OFNotOpenException exceptionWithObject: self];
 
 	if (length > INT_MAX)
 		@throw [OFOutOfRangeException exception];