diff --git a/tests/test_interfaces.py b/tests/test_interfaces.py
new file mode 100644
index 0000000..feb6e25
--- /dev/null
+++ b/tests/test_interfaces.py
@@ -0,0 +1,160 @@
+import os
+import sys
+import importlib
+from datetime import datetime as real_datetime
+
+import requests
+
+
+PROJECT_ROOT = os.path.abspath(os.path.join(os.path.dirname(__file__), ".."))
+if PROJECT_ROOT not in sys.path:
+    sys.path.insert(0, PROJECT_ROOT)
+
+
+def import_interfaces():
+    module_name = "scripts.interfaces"
+    if module_name in sys.modules:
+        del sys.modules[module_name]
+    return importlib.import_module(module_name)
+
+
+def test_create_hostname():
+    interfaces = import_interfaces()
+    assert interfaces.create_hostname("1.2.3.4") == "SDSAT-1234"
+    assert interfaces.create_hostname(None) is None
+
+
+def test_get_public_ip_success(monkeypatch):
+    interfaces = import_interfaces()
+
+    class FakeResp:
+        def json(self):
+            return {"ip": "9.9.9.9"}
+
+    monkeypatch.setattr(interfaces.requests, "get", lambda *args, **kwargs: FakeResp())
+    assert interfaces.get_public_ip() == "9.9.9.9"
+
+
+def test_get_public_ip_failure(monkeypatch):
+    interfaces = import_interfaces()
+
+    def boom(*args, **kwargs):
+        raise requests.RequestException("nope")
+
+    monkeypatch.setattr(interfaces.requests, "get", boom)
+    assert interfaces.get_public_ip() is None
+
+
+def test_get_mac_addresses(monkeypatch):
+    interfaces = import_interfaces()
+
+    # Simule 2 interfaces, dont une sans AF_LINK
+    monkeypatch.setattr(interfaces.netifaces, "interfaces", lambda: ["eth0", "lo"])
+
+    def fake_ifaddresses(name):
+        if name == "eth0":
+            return {interfaces.netifaces.AF_LINK: [{"addr": "AA:BB:CC:DD:EE:FF"}]}
+        return {}  # lo => KeyError sur AF_LINK
+
+    monkeypatch.setattr(interfaces.netifaces, "ifaddresses", fake_ifaddresses)
+
+    assert interfaces.get_mac_addresses() == ["AA:BB:CC:DD:EE:FF"]
+
+
+def test_get_interface_info_found(monkeypatch):
+    interfaces = import_interfaces()
+
+    monkeypatch.setattr(interfaces.netifaces, "interfaces", lambda: ["eth0"])
+
+    def fake_ifaddresses(name):
+        return {
+            interfaces.netifaces.AF_LINK: [{"addr": "AA:BB"}],
+            interfaces.netifaces.AF_INET: [{"addr": "192.168.1.10"}],
+        }
+
+    monkeypatch.setattr(interfaces.netifaces, "ifaddresses", fake_ifaddresses)
+
+    ip, name = interfaces.get_interface_info("AA:BB")
+    assert ip == "192.168.1.10"
+    assert name == "eth0"
+
+
+def test_get_interface_info_not_found(monkeypatch):
+    interfaces = import_interfaces()
+
+    monkeypatch.setattr(interfaces.netifaces, "interfaces", lambda: ["eth0"])
+
+    def fake_ifaddresses(name):
+        return {
+            interfaces.netifaces.AF_LINK: [{"addr": "AA:BB"}],
+            interfaces.netifaces.AF_INET: [{"addr": "192.168.1.10"}],
+        }
+
+    monkeypatch.setattr(interfaces.netifaces, "ifaddresses", fake_ifaddresses)
+
+    ip, name = interfaces.get_interface_info("ZZ:ZZ")
+    assert ip is None
+    assert name is None
+
+
+def test_get_network_interface_info(monkeypatch):
+    interfaces = import_interfaces()
+
+    monkeypatch.setattr(interfaces, "get_mac_addresses", lambda: ["M1", "M2"])
+
+    def fake_get_interface_info(mac):
+        if mac == "M1":
+            return "10.0.0.1", "eth0"
+        return None, None
+
+    monkeypatch.setattr(interfaces, "get_interface_info", fake_get_interface_info)
+
+    assert interfaces.get_network_interface_info() == [("M1", "10.0.0.1", "eth0")]
+
+
+def test_write_log_writes_to_file(monkeypatch, tmp_path):
+    interfaces = import_interfaces()
+
+    # Fixe la date pour un test stable
+    class FakeDateTime:
+        @staticmethod
+        def now():
+            return real_datetime(2025, 1, 2, 3, 4, 5)
+
+        @staticmethod
+        def strftime(fmt):  # pas utilisé ici
+            return ""
+
+    # On patch datetime.datetime.now via le module datetime importé
+    monkeypatch.setattr(interfaces.datetime, "datetime", FakeDateTime)
+
+    interfaces.write_log("hello", log_dir=str(tmp_path))
+
+    log_file = tmp_path / "interfaces_check_log.txt"
+    assert log_file.exists()
+
+    content = log_file.read_text(encoding="utf-8")
+    assert "2025-01-02 03:04:05" in content
+    assert "hello" in content
+
+
+def test_main_runs_without_real_side_effects(monkeypatch, tmp_path):
+    interfaces = import_interfaces()
+
+    # On neutralise les dépendances externes
+    monkeypatch.setattr(interfaces, "get_network_interface_info", lambda: [])
+    monkeypatch.setattr(interfaces, "get_public_ip", lambda: "1.2.3.4")
+
+    # Capture les logs écrits
+    lines = []
+
+    def fake_write_log(action, log_dir=None):
+        lines.append(action)
+
+    monkeypatch.setattr(interfaces, "write_log", fake_write_log)
+
+    interfaces.main(log_dir=str(tmp_path))
+
+    assert "Aucune carte reseau trouvee." in lines
+    assert "Adresse IP publique : 1.2.3.4" in lines
+    assert "Hostname : SDSAT-1234" in lines