diff --git a/server/tracker/services/geo.py b/server/tracker/services/geo.py
new file mode 100644
index 0000000..d509571
--- /dev/null
+++ b/server/tracker/services/geo.py
@@ -0,0 +1,78 @@
+import functools
+import ipaddress
+
+from django.conf import settings
+
+
+def parse_region(raw, new_layout):
+    """ip2region 五段地区串 → {"country", "province", "city"}；不足 4 段/空串返回 None。
+
+    两种数据布局（以 xdb 文件头的结构版本区分）：
+    - 旧版 2.0 结构："国家|区域|省|市|ISP"，省=parts[2]、市=parts[3]；
+    - 新版 3.0 结构（现行 v4/v6 库）："国家|省/区域|城市|ISP|国家代码"，
+      省=parts[1]、市=parts[2]，ISP 段在 parts[3]——映射错位会把 ISP 串进 city。
+    缺失段为 ip2region 的 "0" 占位，原样保留，由展示层决定如何呈现。
+    """
+    parts = (raw or "").split("|")
+    if len(parts) < 4:
+        return None
+    if new_layout:
+        country, province, city = parts[0], parts[1], parts[2]
+    else:
+        country, province, city = parts[0], parts[2], parts[3]
+    return {"country": country, "province": province, "city": city}
+
+
+class GeoResolver:
+    """离线 IP 地理解析（ip2region xdb，进程级单例）。
+
+    py-ip2region 3.0.4 实际 API（以其源码为准，与官方旧 README 不同）：
+    - ``searcher.new_with_buffer(version, c_buffer)`` 需要先传 ``util.IPv4``/``util.IPv6``
+      版本对象（由 xdb 文件头 256 字节经 ``util.Header`` + ``util.version_from_header``
+      探测；2.0 结构老库自动归为 IPv4）；
+    - ``Searcher`` 不支持 with 上下文管理器（无 __enter__/__exit__）；
+    - c_buffer 模式下 ``search(ip)`` 是纯内存切片（无文件 IO、无共享可变状态，
+      官方声明线程安全），返回上述五段字符串。
+
+    包缺失 / xdb 未下载 / 文件损坏时优雅降级：resolve 一律返回 None。
+    """
+
+    def __init__(self):
+        self._searcher = None
+        self._new_layout = True
+        try:
+            from ip2region import searcher as ip2region_searcher
+            from ip2region import util as ip2region_util
+
+            with open(settings.IP2REGION_XDB, "rb") as f:
+                buff = f.read()
+            if len(buff) < ip2region_util.HeaderInfoLength:
+                return  # 文件过短，绝非合法 xdb
+            header = ip2region_util.Header(buff[: ip2region_util.HeaderInfoLength])
+            version = ip2region_util.version_from_header(header)
+            if version is None:
+                return  # 无法识别的 xdb 结构/IP 版本
+            # 结构版本同时决定数据段布局：2.0 旧布局 / 3.0 新布局
+            self._new_layout = header.version >= ip2region_util.XdbStructure30
+            self._searcher = ip2region_searcher.new_with_buffer(version, buff)
+        except Exception:
+            self._searcher = None
+
+    @functools.lru_cache(maxsize=10000)
+    def resolve(self, ip: str):
+        """返回 {"country", "province", "city"}，内网/环回/非法 IP 或降级时返回 None。
+        结果被 lru_cache 缓存（键含 self，单例常驻故无泄漏问题），调用方勿修改返回的 dict。"""
+        if not ip:
+            return None
+        try:
+            if ipaddress.ip_address(ip).is_private:
+                return None
+        except ValueError:
+            return None
+        if not self._searcher:
+            return None
+        try:
+            raw = self._searcher.search(ip)
+            return parse_region(raw, self._new_layout)
+        except Exception:
+            return None
diff --git a/server/tracker/tests/test_geo.py b/server/tracker/tests/test_geo.py
new file mode 100644
index 0000000..88e09e8
--- /dev/null
+++ b/server/tracker/tests/test_geo.py
@@ -0,0 +1,73 @@
+import os
+
+import pytest
+from django.conf import settings
+
+from tracker.services.geo import GeoResolver, parse_region
+
+XDB_EXISTS = os.path.exists(settings.IP2REGION_XDB)
+
+
+def test_private_ip_returns_local():
+    r = GeoResolver()
+    assert r.resolve("192.168.1.5") is None       # 内网不解析（后台显示"本地"）
+    assert r.resolve("127.0.0.1") is None
+
+
+def test_public_ip_parsed_or_none(monkeypatch):
+    r = GeoResolver()
+    # xdb 未下载/解析失败时优雅降级返回 None，不抛异常
+    out = r.resolve("8.8.8.8")
+    assert out is None or set(out) == {"country", "province", "city"}
+
+
+def test_parse_region_two_layouts():
+    # 旧版 2.0 结构："国家|区域|省|市|ISP"
+    assert parse_region("中国|0|江苏省|南京市|电信", new_layout=False) == {
+        "country": "中国", "province": "江苏省", "city": "南京市"}
+    # 新版 3.0 结构（v4/v6 库）："国家|省/区域|城市|ISP|国家代码"
+    assert parse_region("中国|江苏省|南京市|0|CN", new_layout=True) == {
+        "country": "中国", "province": "江苏省", "city": "南京市"}
+    # ISP 段不得串进 city
+    assert parse_region("United States|California|0|Google LLC|US", new_layout=True) == {
+        "country": "United States", "province": "California", "city": "0"}
+    assert parse_region("", new_layout=True) is None
+    assert parse_region("中国", new_layout=True) is None      # 不足 4 段
+    assert parse_region(None, new_layout=False) is None
+
+
+class _FakeSearcher:
+    def __init__(self, raw):
+        self._raw = raw
+
+    def search(self, ip):
+        return self._raw
+
+
+def test_resolve_uses_layout_dispatch():
+    r = GeoResolver()
+    r._searcher = _FakeSearcher("中国|北京市|北京市|百度|CN")
+    r._new_layout = True
+    assert r.resolve("1.2.3.4") == {
+        "country": "中国", "province": "北京市", "city": "北京市"}
+
+    r2 = GeoResolver()
+    r2._searcher = _FakeSearcher("中国|华北|北京市|北京市|百度")
+    r2._new_layout = False
+    assert r2.resolve("1.2.3.4") == {
+        "country": "中国", "province": "北京市", "city": "北京市"}
+
+
+@pytest.mark.skipif(not XDB_EXISTS, reason="ip2region.xdb 未下载，跳过真实解析探针")
+def test_real_probe_public_ip():
+    r = GeoResolver()
+    assert r._searcher is not None, "xdb 存在时必须成功加载"
+    raw = r._searcher.search("8.8.8.8")
+    assert len(raw.split("|")) == 5, f"应为五段格式，实际: {raw!r}"
+    out = r.resolve("8.8.8.8")
+    assert set(out) == {"country", "province", "city"}
+    assert out["country"] in ("美国", "United States")
+    assert out["city"] != "Google LLC", "ISP 不得串进 city（布局映射错误）"
+    cn = r.resolve("114.114.114.114")
+    assert cn["country"] == "中国"
+    assert cn["province"] not in ("", "0"), "国内公网 IP 应解析出省份"