diff --git a/arch/sim/src/sim/vpnkit/negotiate.c b/arch/sim/src/sim/vpnkit/negotiate.c
new file mode 100644
index 00000000000..0df758ae68b
--- /dev/null
+++ b/arch/sim/src/sim/vpnkit/negotiate.c
@@ -0,0 +1,58 @@
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+
+#include "protocol.h"
+
+#define ERROR(fmt, ...) \
+        fprintf(stderr, "up_vpnkit: " fmt "\r\n", ##__VA_ARGS__)
+#define INFO(fmt, ...) \
+        fprintf(stderr, "up_vpnkit: " fmt "\r\n", ##__VA_ARGS__)
+
+/* Negotiate a vmnet connection, returns 0 on success and 1 on error. */
+int negotiate(int fd, struct vif_info *vif)
+{
+	enum command command = ethernet;
+	struct init_message *me;
+	struct ethernet_args args;
+	struct init_message you;
+	char *txt;
+
+	me = create_init_message();
+	if (!me)
+		goto err;
+
+	if (write_init_message(fd, me) == -1)
+		goto err;
+
+	if (read_init_message(fd, &you) == -1)
+		goto err;
+
+	if (me->version != you.version) {
+		ERROR("Server did not accept our protocol version (client: %d, server: %d)", me->version, you.version);
+		goto err;
+	}
+
+	txt = print_init_message(&you);
+	if (!txt)
+		goto err;
+
+	INFO("Server reports %s", txt);
+	free(txt);
+
+	if (write_command(fd, &command) == -1)
+		goto err;
+
+	/* We don't need a uuid */
+	memset(&args.uuid_string[0], 0, sizeof(args.uuid_string));
+	if (write_ethernet_args(fd, &args) == -1)
+		goto err;
+
+	if (read_vif_response(fd, vif) == -1)
+		goto err;
+
+	return 0;
+err:
+	ERROR("Failed to negotiate vmnet connection");
+	return 1;
+}