diff --git a/Cargo.toml b/Cargo.toml
index dc7a089..14a836c 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -1,6 +1,6 @@
 [package]
 name = "rust_util"
-version = "0.6.3"
+version = "0.6.5"
 authors = ["Hatter Jiang <jht5945@gmail.com>"]
 edition = "2018"
 description = "Hatter's Rust Util"
diff --git a/src/lib.rs b/src/lib.rs
index 6db3ce8..4348ae2 100644
--- a/src/lib.rs
+++ b/src/lib.rs
@@ -13,6 +13,7 @@ pub mod util_str;
 pub mod util_size;
 pub mod util_file;
 pub mod util_time;
+pub mod util_net;
 
 /// iff!(condition, result_when_true, result_when_false)
 #[macro_export] macro_rules! iff {
diff --git a/src/util_net.rs b/src/util_net.rs
new file mode 100644
index 0000000..58e3dd2
--- /dev/null
+++ b/src/util_net.rs
@@ -0,0 +1,95 @@
+use std::net::SocketAddr;
+use crate::XResult;
+
+#[derive(Debug, Clone)]
+pub enum IpAddressMask {
+    Ipv4([u8; 4], u8),
+}
+
+impl IpAddressMask {
+    pub fn parse_ipv4(addr: &str) -> Option<Self> {
+        let addr_mask_parts = addr.split('/').collect::<Vec<_>>();
+        let (addr_ip, mask) = if addr_mask_parts.len() == 1 {
+            (addr_mask_parts[0], 32)
+        } else if addr_mask_parts.len() == 2 {
+            if let Ok(mask) = addr_mask_parts[1].parse::<u8>() {
+                (addr_mask_parts[0], mask)
+            } else {
+                return None;
+            }
+        } else {
+            return None;
+        };
+        let addr_parts = addr_ip.split('.').collect::<Vec<_>>();
+        if addr_parts.len() != 4 {
+            return None;
+        }
+        let parsed_addr = || -> XResult<[u8; 4]> {
+            Ok([addr_parts[0].parse::<u8>()?,
+                addr_parts[1].parse::<u8>()?,
+                addr_parts[2].parse::<u8>()?,
+                addr_parts[3].parse::<u8>()?
+            ])
+        };
+        match parsed_addr() {
+            Ok(parts) => Some(IpAddressMask::Ipv4(parts, mask)),
+            Err(_) => None,
+        }
+    }
+
+    pub fn to_address(&self) -> String {
+        match self {
+            IpAddressMask::Ipv4(ipv4, mask) => {
+                format!("{}/{}", ipv4.iter().map(|p| p.to_string()).collect::<Vec<_>>().join("."), mask)
+            },
+        }
+    }
+
+    pub fn is_matches(&self, socket_addr: &SocketAddr) -> bool {
+        match socket_addr {
+            SocketAddr::V4(socket_addr_v4) => {
+                let socket_addr_v4_octets = socket_addr_v4.ip().octets();
+                match self {
+                    IpAddressMask::Ipv4(self_ipv4_octets, mask) => {
+                        let self_ipv4_u32 = ipv4_to_u32(&self_ipv4_octets);
+                        let addr_ipv4_u32 = ipv4_to_u32(&socket_addr_v4_octets);
+                        let mask_u32 = ipv4_mask(*mask);
+                        self_ipv4_u32 & mask_u32 == addr_ipv4_u32 & mask_u32
+                    },
+                }
+            },
+            SocketAddr::V6(_) => false,
+        }
+    }
+}
+
+fn ipv4_mask(mask: u8) -> u32 {
+    let mut r = 0_u32;
+    for _ in 0..mask {
+        r <<= 1;
+        r |= 1;
+    }
+    for _ in mask..32 {
+        r <<= 1;
+    }
+    r
+}
+
+fn ipv4_to_u32(ipv4: &[u8; 4]) -> u32 {
+    ((ipv4[0] as u32) << (8 * 3)) + ((ipv4[1] as u32) << (8 * 2)) + ((ipv4[2] as u32) << 8) + (ipv4[3] as u32)
+}
+
+
+#[test]
+fn test_is_matches() {
+    let addr = SocketAddr::new(std::net::IpAddr::V4(std::net::Ipv4Addr::new(127, 0, 0, 1)), 123);
+    let addr2 = SocketAddr::new(std::net::IpAddr::V4(std::net::Ipv4Addr::new(127, 0, 0, 2)), 123);
+   assert_eq!(true, IpAddressMask::parse_ipv4("127.0.0.1").unwrap().is_matches(&addr));
+   assert_eq!(true, IpAddressMask::parse_ipv4("127.0.0.1/32").unwrap().is_matches(&addr));
+   assert_eq!(true, IpAddressMask::parse_ipv4("127.0.0.1/31").unwrap().is_matches(&addr));
+   assert_eq!(true, IpAddressMask::parse_ipv4("127.0.0.1/30").unwrap().is_matches(&addr));
+   assert_eq!(false, IpAddressMask::parse_ipv4("127.0.0.1").unwrap().is_matches(&addr2));
+   assert_eq!(false, IpAddressMask::parse_ipv4("127.0.0.1/32").unwrap().is_matches(&addr2));
+   assert_eq!(false, IpAddressMask::parse_ipv4("127.0.0.1/31").unwrap().is_matches(&addr2));
+   assert_eq!(true, IpAddressMask::parse_ipv4("127.0.0.1/30").unwrap().is_matches(&addr2));
+}
\ No newline at end of file