diff --git a/nchan.c b/nchan.c
new file mode 100644
index 0000000..fcaeae4
--- /dev/null
+++ b/nchan.c
@@ -0,0 +1,187 @@
+#include "includes.h"
+RCSID("$Id: nchan.c,v 1.1 1999/10/27 03:42:44 damien Exp $");
+
+#include "ssh.h"
+
+#include "buffer.h"
+#include "packet.h"
+#include "channels.h"
+#include "nchan.h"
+
+static void chan_send_ieof(Channel *c);
+static void chan_send_oclose(Channel *c);
+static void chan_shutdown_write(Channel *c);
+static void chan_shutdown_read(Channel *c);
+static void chan_delele_if_full_closed(Channel *c);
+
+/*
+ * EVENTS: update channel input/output states
+ *	   execute ACTIONS
+ */
+/* events concerning the INPUT from socket for channel (istate) */
+void
+chan_rcvd_oclose(Channel *c){
+	switch(c->istate){
+	case CHAN_INPUT_WAIT_OCLOSE:
+		debug("channel %d: INPUT_WAIT_OCLOSE -> INPUT_CLOSED [rcvd OCLOSE]", c->self);
+		c->istate=CHAN_INPUT_CLOSED;
+		chan_delele_if_full_closed(c);
+		break;
+	case CHAN_INPUT_OPEN:
+		debug("channel %d: INPUT_OPEN -> INPUT_CLOSED [rvcd OCLOSE, send IEOF]", c->self);
+		chan_shutdown_read(c);
+		chan_send_ieof(c);
+		c->istate=CHAN_INPUT_CLOSED;
+		chan_delele_if_full_closed(c);
+		break;
+	default:
+		debug("protocol error: chan_rcvd_oclose %d for istate %d",c->self,c->istate);
+		break;
+	}
+}
+void
+chan_read_failed(Channel *c){
+	switch(c->istate){
+	case CHAN_INPUT_OPEN:
+		debug("channel %d: INPUT_OPEN -> INPUT_WAIT_DRAIN [read failed]", c->self);
+		chan_shutdown_read(c);
+		c->istate=CHAN_INPUT_WAIT_DRAIN;
+		break;
+	default:
+		debug("internal error: we do not read, but chan_read_failed %d for istate %d",
+			c->self,c->istate);
+		break;
+	}
+}
+void
+chan_ibuf_empty(Channel *c){
+	if(buffer_len(&c->input)){
+		debug("internal error: chan_ibuf_empty %d for non empty buffer",c->self);
+		return;
+	}
+	switch(c->istate){
+	case CHAN_INPUT_WAIT_DRAIN:
+		debug("channel %d: INPUT_WAIT_DRAIN -> INPUT_WAIT_OCLOSE [inbuf empty, send IEOF]", c->self);
+		chan_send_ieof(c);
+		c->istate=CHAN_INPUT_WAIT_OCLOSE;
+		break;
+	default:
+		debug("internal error: chan_ibuf_empty %d for istate %d",c->self,c->istate);
+		break;
+	}
+}
+/* events concerning the OUTPUT from channel for socket (ostate) */
+void
+chan_rcvd_ieof(Channel *c){
+	switch(c->ostate){
+	case CHAN_OUTPUT_OPEN:
+		debug("channel %d: OUTPUT_OPEN -> OUTPUT_WAIT_DRAIN [rvcd IEOF]", c->self);
+		c->ostate=CHAN_OUTPUT_WAIT_DRAIN;
+		break;
+	case CHAN_OUTPUT_WAIT_IEOF:
+		debug("channel %d: OUTPUT_WAIT_IEOF -> OUTPUT_CLOSED [rvcd IEOF]", c->self);
+		c->ostate=CHAN_OUTPUT_CLOSED;
+		chan_delele_if_full_closed(c);
+		break;
+	default:
+		debug("protocol error: chan_rcvd_ieof %d for ostate %d", c->self,c->ostate);
+		break;
+	}
+}
+void
+chan_write_failed(Channel *c){
+	switch(c->ostate){
+	case CHAN_OUTPUT_OPEN:
+		debug("channel %d: OUTPUT_OPEN -> OUTPUT_WAIT_IEOF [write failed]", c->self);
+		chan_send_oclose(c);
+		c->ostate=CHAN_OUTPUT_WAIT_IEOF;
+		break;
+	case CHAN_OUTPUT_WAIT_DRAIN:
+		debug("channel %d: OUTPUT_WAIT_DRAIN -> OUTPUT_CLOSED [write failed]", c->self);
+		chan_send_oclose(c);
+		c->ostate=CHAN_OUTPUT_CLOSED;
+		chan_delele_if_full_closed(c);
+		break;
+	default:
+		debug("internal error: chan_write_failed %d for ostate %d",c->self,c->ostate);
+		break;
+	}
+}
+void
+chan_obuf_empty(Channel *c){
+	if(buffer_len(&c->output)){
+		debug("internal error: chan_obuf_empty %d for non empty buffer",c->self);
+		return;
+	}
+	switch(c->ostate){
+	case CHAN_OUTPUT_WAIT_DRAIN:
+		debug("channel %d: OUTPUT_WAIT_DRAIN -> OUTPUT_CLOSED [obuf empty, send OCLOSE]", c->self);
+		chan_send_oclose(c);
+		c->ostate=CHAN_OUTPUT_CLOSED;
+		chan_delele_if_full_closed(c);
+		break;
+	default:
+		debug("internal error: chan_obuf_empty %d for ostate %d",c->self,c->ostate);
+		break;
+	}
+}
+/*
+ * ACTIONS: should never update c->istate or c->ostate
+ */
+static void
+chan_send_ieof(Channel *c){
+	switch(c->istate){
+	case CHAN_INPUT_OPEN:
+	case CHAN_INPUT_WAIT_DRAIN:
+		packet_start(SSH_MSG_CHANNEL_INPUT_EOF);
+		packet_put_int(c->remote_id);
+		packet_send();
+		break;
+	default:
+		debug("internal error: channel %d: cannot send IEOF for istate %d",c->self,c->istate);
+		break;
+	}
+}
+static void
+chan_send_oclose(Channel *c){
+	switch(c->ostate){
+	case CHAN_OUTPUT_OPEN:
+	case CHAN_OUTPUT_WAIT_DRAIN:
+		chan_shutdown_write(c);
+		buffer_consume(&c->output, buffer_len(&c->output));
+		packet_start(SSH_MSG_CHANNEL_OUTPUT_CLOSE);
+		packet_put_int(c->remote_id);
+		packet_send();
+		break;
+	default:
+		debug("internal error: channel %d: cannot send OCLOSE for ostate %d",c->self,c->istate);
+		break;
+	}
+}
+/* helper */
+static void
+chan_shutdown_write(Channel *c){
+	debug("channel %d: shutdown_write", c->self);
+	if(shutdown(c->sock, SHUT_WR)<0)
+		error("chan_shutdown_write failed for #%d/fd%d: %.100s",
+			c->self, c->sock, strerror(errno));
+}
+static void
+chan_shutdown_read(Channel *c){
+	debug("channel %d: shutdown_read", c->self);
+	if(shutdown(c->sock, SHUT_RD)<0)
+		error("chan_shutdown_read failed for #%d/fd%d: %.100s",
+			c->self, c->sock, strerror(errno));
+}
+static void
+chan_delele_if_full_closed(Channel *c){
+	if(c->istate==CHAN_INPUT_CLOSED && c->ostate==CHAN_OUTPUT_CLOSED){
+		debug("channel %d: closing", c->self);
+		channel_free(c->self);
+	}
+}
+void
+chan_init_iostates(Channel *c){
+	c->ostate=CHAN_OUTPUT_OPEN;
+	c->istate=CHAN_INPUT_OPEN;
+}