--- /dev/null
+/* SPDX-License-Identifier: GPL-2.0 WITH Linux-syscall-note */
+/*
+ * Swansea University Computer Society NET3
+ *
+ * This file declares the constants of special use with the SLIP/CSLIP/
+ * KISS TNC driver.
+ */
+
+#ifndef __LINUX_SLIP_H
+#define __LINUX_SLIP_H
+
+#define SL_MODE_SLIP 0
+#define SL_MODE_CSLIP 1
+#define SL_MODE_KISS 4
+
+#define SL_OPT_SIXBIT 2
+#define SL_OPT_ADAPTIVE 8
+
+/*
+ * VSV = ioctl for keepalive & outfill in SLIP driver
+ */
+
+#define SIOCSKEEPALIVE (SIOCDEVPRIVATE) /* Set keepalive timeout in sec */
+#define SIOCGKEEPALIVE (SIOCDEVPRIVATE+1) /* Get keepalive timeout */
+#define SIOCSOUTFILL (SIOCDEVPRIVATE+2) /* Set outfill timeout */
+#define SIOCGOUTFILL (SIOCDEVPRIVATE+3) /* Get outfill timeout */
+#define SIOCSLEASE (SIOCDEVPRIVATE+4) /* Set "leased" line type */
+#define SIOCGLEASE (SIOCDEVPRIVATE+5) /* Get line type */
+
+
+#endif