diff --git a/src/asn1helpers.c b/src/asn1helpers.c
index 436afa5..36702c0 100644
--- a/src/asn1helpers.c
+++ b/src/asn1helpers.c
@@ -1,3 +1,22 @@
+/* helper functions to dela with asn1c data types */
+
+/* (C) 2014-2015 by Harald Welte <laforge@gnumonks.org>
+ * All Rights Reserved
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU Affero General Public License as published by
+ * the Free Software Foundation; either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU Affero General Public License for more details.
+ *
+ * You should have received a copy of the GNU Affero General Public License
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ *
+ */
 
 #include <string.h>
 
diff --git a/src/hnbap_common.c b/src/hnbap_common.c
index 0982a02..02860a7 100644
--- a/src/hnbap_common.c
+++ b/src/hnbap_common.c
@@ -1,3 +1,24 @@
+/* HNBAP common code */
+
+/* (C) 2015 by Harald Welte <laforge@gnumonks.org>
+ * All Rights Reserved
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU Affero General Public License as published by
+ * the Free Software Foundation; either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU Affero General Public License for more details.
+ *
+ * You should have received a copy of the GNU Affero General Public License
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ *
+ */
+
+
 #include <stdint.h>
 
 #include <osmocom/core/msgb.h>
diff --git a/src/hnbgw.c b/src/hnbgw.c
index d26f166..651c008 100644
--- a/src/hnbgw.c
+++ b/src/hnbgw.c
@@ -1,3 +1,23 @@
+/* main application for hnb-gw part of osmo-iuh */
+
+/* (C) 2015 by Harald Welte <laforge@gnumonks.org>
+ * All Rights Reserved
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU Affero General Public License as published by
+ * the Free Software Foundation; either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU Affero General Public License for more details.
+ *
+ * You should have received a copy of the GNU Affero General Public License
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ *
+ */
+
 #include <unistd.h>
 #include <stdio.h>
 #include <stdlib.h>
diff --git a/src/hnbgw_hnbap.c b/src/hnbgw_hnbap.c
index 4896f34..3e3715c 100644
--- a/src/hnbgw_hnbap.c
+++ b/src/hnbgw_hnbap.c
@@ -1,3 +1,23 @@
+/* hnb-gw specific code for HNBAP */
+
+/* (C) 2015 by Harald Welte <laforge@gnumonks.org>
+ * All Rights Reserved
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU Affero General Public License as published by
+ * the Free Software Foundation; either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU Affero General Public License for more details.
+ *
+ * You should have received a copy of the GNU Affero General Public License
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ *
+ */
+
 #include <osmocom/core/msgb.h>
 #include <osmocom/core/utils.h>
 #include <osmocom/gsm/gsm48.h>
diff --git a/src/hnbgw_ranap.c b/src/hnbgw_ranap.c
index 6dda81e..15efb85 100644
--- a/src/hnbgw_ranap.c
+++ b/src/hnbgw_ranap.c
@@ -1,3 +1,25 @@
+/* hnb-gw specific code for RANAP */
+
+/* (C) 2015 by Harald Welte <laforge@gnumonks.org>
+ * All Rights Reserved
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU Affero General Public License as published by
+ * the Free Software Foundation; either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU Affero General Public License for more details.
+ *
+ * You should have received a copy of the GNU Affero General Public License
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ *
+ */
+
+
+
 #include <osmocom/core/msgb.h>
 #include <osmocom/core/utils.h>
 #include <osmocom/gsm/gsm48.h>
diff --git a/src/hnbgw_rua.c b/src/hnbgw_rua.c
index 4cc10ac..cca09ad 100644
--- a/src/hnbgw_rua.c
+++ b/src/hnbgw_rua.c
@@ -1,3 +1,24 @@
+/* hnb-gw specific code for RUA (Ranap User Adaption) */
+
+/* (C) 2015 by Harald Welte <laforge@gnumonks.org>
+ * All Rights Reserved
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU Affero General Public License as published by
+ * the Free Software Foundation; either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU Affero General Public License for more details.
+ *
+ * You should have received a copy of the GNU Affero General Public License
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ *
+ */
+
+
 #include <osmocom/core/msgb.h>
 #include <osmocom/core/utils.h>
 
diff --git a/src/iu_helpers.c b/src/iu_helpers.c
index bc87905..dfe47d6 100644
--- a/src/iu_helpers.c
+++ b/src/iu_helpers.c
@@ -1,8 +1,29 @@
+/* Iu interface specific helper functions */
+
+/* (C) 2015 by Harald Welte <laforge@gnumonks.org>
+ * All Rights Reserved
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU Affero General Public License as published by
+ * the Free Software Foundation; either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU Affero General Public License for more details.
+ *
+ * You should have received a copy of the GNU Affero General Public License
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ *
+ */
+
 #include <stdint.h>
 #include <string.h>
 
 #include <osmocom/core/utils.h>
 
+/* decode a BCD-string as used inside ASN.1 encoded Iu interface protocols */
 int decode_iu_bcd(char *out, size_t out_len, const uint8_t *in, size_t in_len)
 {
 	const uint8_t *ch;
@@ -23,6 +44,7 @@
 	return outch - out;
 }
 
+/* decode an IMSI as used inside ASN.1 encoded Iu interface protocols */
 int encode_iu_imsi(uint8_t *out, size_t out_len, const char *in)
 {
 	unsigned int len = strlen(in);
diff --git a/src/ranap_common.c b/src/ranap_common.c
index dc86a7a..ce97899 100644
--- a/src/ranap_common.c
+++ b/src/ranap_common.c
@@ -1,3 +1,23 @@
+/* common RANAP code */
+
+/* (C) 2015 by Harald Welte <laforge@gnumonks.org>
+ * All Rights Reserved
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU Affero General Public License as published by
+ * the Free Software Foundation; either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU Affero General Public License for more details.
+ *
+ * You should have received a copy of the GNU Affero General Public License
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ *
+ */
+
 #include <stdint.h>
 
 #include <osmocom/core/msgb.h>
diff --git a/src/rua_common.c b/src/rua_common.c
index 8f4da12..554896b 100644
--- a/src/rua_common.c
+++ b/src/rua_common.c
@@ -1,3 +1,24 @@
+/* common RUA (RANAP User Adaption) Code */
+
+/* (C) 2015 by Harald Welte <laforge@gnumonks.org>
+ * All Rights Reserved
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU Affero General Public License as published by
+ * the Free Software Foundation; either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU Affero General Public License for more details.
+ *
+ * You should have received a copy of the GNU Affero General Public License
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ *
+ */
+
+
 #include <stdint.h>
 
 #include <osmocom/core/msgb.h>
diff --git a/src/tests/test-helpers.c b/src/tests/test-helpers.c
index e23f017..b299841 100644
--- a/src/tests/test-helpers.c
+++ b/src/tests/test-helpers.c
@@ -1,3 +1,24 @@
+/* some humble start of unit testing */
+
+/* (C) 2015 by Harald Welte <laforge@gnumonks.org>
+ * All Rights Reserved
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU Affero General Public License as published by
+ * the Free Software Foundation; either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU Affero General Public License for more details.
+ *
+ * You should have received a copy of the GNU Affero General Public License
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ *
+ */
+
+
 #include "iu_helpers.h"
 #include "asn1helpers.h"