diff --git a/libs/hbb_common/src/socket_client.rs b/libs/hbb_common/src/socket_client.rs
index b7cb13754..dde237267 100644
--- a/libs/hbb_common/src/socket_client.rs
+++ b/libs/hbb_common/src/socket_client.rs
@@ -9,17 +9,54 @@ use std::net::SocketAddr;
 use tokio::net::ToSocketAddrs;
 use tokio_socks::{IntoTargetAddr, TargetAddr};
 
-pub fn test_if_valid_server(host: &str) -> String {
-    let mut host = host.to_owned();
-    if !host.contains(":") {
-        host = format!("{}:{}", host, 0);
+#[inline]
+pub fn check_port<T: std::string::ToString>(host: T, port: i32) -> String {
+    let host = host.to_string();
+    if crate::is_ipv6_str(&host) {
+        if host.starts_with("[") {
+            return host;
+        }
+        return format!("[{}]:{}", host, port);
     }
+    if !host.contains(":") {
+        return format!("{}:{}", host, port);
+    }
+    return host;
+}
+
+#[inline]
+pub fn increase_port<T: std::string::ToString>(host: T, offset: i32) -> String {
+    let host = host.to_string();
+    if crate::is_ipv6_str(&host) {
+        if host.starts_with("[") {
+            let tmp: Vec<&str> = host.split("]:").collect();
+            if tmp.len() == 2 {
+                let port: i32 = tmp[1].parse().unwrap_or(0);
+                if port > 0 {
+                    return format!("{}]:{}", tmp[0], port + offset);
+                }
+            }
+        }
+    } else if host.contains(":") {
+        let tmp: Vec<&str> = host.split(":").collect();
+        if tmp.len() == 2 {
+            let port: i32 = tmp[1].parse().unwrap_or(0);
+            if port > 0 {
+                return format!("{}:{}", tmp[0], port + offset);
+            }
+        }
+    }
+    return host;
+}
+
+pub fn test_if_valid_server(host: &str) -> String {
+    let host = check_port(host, 0);
 
     use std::net::ToSocketAddrs;
     match Config::get_network_type() {
         NetworkType::Direct => match host.to_socket_addrs() {
             Err(err) => err.to_string(),
-            Ok(_) => "".to_owned(),
+            Ok(x) => "".to_owned(),
         },
         NetworkType::ProxySocks => match &host.into_target_addr() {
             Err(err) => err.to_string(),
@@ -216,4 +253,30 @@ mod tests {
         }
         assert!(query_nip_io(&"1.1.1.1:80".parse().unwrap()).await.is_err());
     }
+
+    #[test]
+    fn test_test_if_valid_server() {
+        assert!(!test_if_valid_server("a").is_empty());
+        // on Linux, "1" is resolved to "0.0.0.1"
+        assert!(test_if_valid_server("1.1.1.1").is_empty());
+        assert!(test_if_valid_server("1.1.1.1:1").is_empty());
+    }
+
+    #[test]
+    fn test_check_port() {
+        assert_eq!(check_port("[1:2]:12", 32), "[1:2]:12");
+        assert_eq!(check_port("1:2", 32), "[1:2]:32");
+        assert_eq!(check_port("z1:2", 32), "z1:2");
+        assert_eq!(check_port("1.1.1.1", 32), "1.1.1.1:32");
+        assert_eq!(check_port("1.1.1.1:32", 32), "1.1.1.1:32");
+        assert_eq!(check_port("test.com:32", 0), "test.com:32");
+        assert_eq!(increase_port("[1:2]:12", 1), "[1:2]:13");
+        assert_eq!(increase_port("1.2.2.4:12", 1), "1.2.2.4:13");
+        assert_eq!(increase_port("1.2.2.4", 1), "1.2.2.4");
+        assert_eq!(increase_port("test.com", 1), "test.com");
+        assert_eq!(increase_port("test.com:13", 4), "test.com:17");
+        assert_eq!(increase_port("1:13", 4), "1:13");
+        assert_eq!(increase_port("22:1:13", 4), "22:1:13");
+        assert_eq!(increase_port("z1:2", 1), "z1:3");
+    }
 }
diff --git a/src/common.rs b/src/common.rs
index 254c910e6..96a7763d0 100644
--- a/src/common.rs
+++ b/src/common.rs
@@ -476,42 +476,12 @@ pub fn username() -> String {
 
 #[inline]
 pub fn check_port<T: std::string::ToString>(host: T, port: i32) -> String {
-    let host = host.to_string();
-    if is_ipv6_str(&host) {
-        if host.starts_with("[") {
-            return host;
-        }
-        return format!("[{}]:{}", host, port);
-    }
-    if !host.contains(":") {
-        return format!("{}:{}", host, port);
-    }
-    return host;
+    hbb_common::socket_client::check_port(host, port)
 }
 
 #[inline]
 pub fn increase_port<T: std::string::ToString>(host: T, offset: i32) -> String {
-    let host = host.to_string();
-    if is_ipv6_str(&host) {
-        if host.starts_with("[") {
-            let tmp: Vec<&str> = host.split("]:").collect();
-            if tmp.len() == 2 {
-                let port: i32 = tmp[1].parse().unwrap_or(0);
-                if port > 0 {
-                    return format!("{}]:{}", tmp[0], port + offset);
-                }
-            }
-        }
-    } else if host.contains(":") {
-        let tmp: Vec<&str> = host.split(":").collect();
-        if tmp.len() == 2 {
-            let port: i32 = tmp[1].parse().unwrap_or(0);
-            if port > 0 {
-                return format!("{}:{}", tmp[0], port + offset);
-            }
-        }
-    }
-    return host;
+    hbb_common::socket_client::increase_port(host, offset)
 }
 
 pub const POSTFIX_SERVICE: &'static str = "_service";
@@ -741,22 +711,4 @@ pub fn make_fd_to_json(id: i32, path: String, entries: &Vec<FileEntry>) -> Strin
 #[cfg(test)]
 mod test_common {
     use super::*;
-
-    #[test]
-    fn test_check_port() {
-        assert_eq!(check_port("[1:2]:12", 32), "[1:2]:12");
-        assert_eq!(check_port("1:2", 32), "[1:2]:32");
-        assert_eq!(check_port("z1:2", 32), "z1:2");
-        assert_eq!(check_port("1.1.1.1", 32), "1.1.1.1:32");
-        assert_eq!(check_port("1.1.1.1:32", 32), "1.1.1.1:32");
-        assert_eq!(check_port("test.com:32", 0), "test.com:32");
-        assert_eq!(increase_port("[1:2]:12", 1), "[1:2]:13");
-        assert_eq!(increase_port("1.2.2.4:12", 1), "1.2.2.4:13");
-        assert_eq!(increase_port("1.2.2.4", 1), "1.2.2.4");
-        assert_eq!(increase_port("test.com", 1), "test.com");
-        assert_eq!(increase_port("test.com:13", 4), "test.com:17");
-        assert_eq!(increase_port("1:13", 4), "1:13");
-        assert_eq!(increase_port("22:1:13", 4), "22:1:13");
-        assert_eq!(increase_port("z1:2", 1), "z1:3");
-    }
 }