diff --git a/Cargo.lock b/Cargo.lock
index f046aa4715b9..c6f0395f821f 100644
--- a/Cargo.lock
+++ b/Cargo.lock
@@ -104,7 +104,7 @@ source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "e6437fb0cbb35301d1ca48d584e7e035823a4b34163924a35cd80d12ec3358a7"
 dependencies = [
  "bit-vec",
- "rand",
+ "rand 0.7.3",
  "siphasher",
 ]
 
@@ -459,6 +459,17 @@ dependencies = [
  "wasi 0.9.0+wasi-snapshot-preview1",
 ]
 
+[[package]]
+name = "getrandom"
+version = "0.2.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "ee8025cf36f917e6a52cce185b7c7177689b838b7ec138364e50cc2277a56cf4"
+dependencies = [
+ "cfg-if 0.1.10",
+ "libc",
+ "wasi 0.9.0+wasi-snapshot-preview1",
+]
+
 [[package]]
 name = "h2"
 version = "0.3.0"
@@ -1139,11 +1150,23 @@ version = "0.7.3"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "6a6b1679d49b24bbfe0c803429aa1874472f50d9b363131f0e89fc356b544d03"
 dependencies = [
- "getrandom",
+ "getrandom 0.1.15",
  "libc",
- "rand_chacha",
- "rand_core",
- "rand_hc",
+ "rand_chacha 0.2.2",
+ "rand_core 0.5.1",
+ "rand_hc 0.2.0",
+]
+
+[[package]]
+name = "rand"
+version = "0.8.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "a76330fb486679b4ace3670f117bbc9e16204005c4bde9c4bd372f45bed34f12"
+dependencies = [
+ "libc",
+ "rand_chacha 0.3.0",
+ "rand_core 0.6.0",
+ "rand_hc 0.3.0",
 ]
 
 [[package]]
@@ -1153,7 +1176,17 @@ source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "f4c8ed856279c9737206bf725bf36935d8666ead7aa69b52be55af369d193402"
 dependencies = [
  "ppv-lite86",
- "rand_core",
+ "rand_core 0.5.1",
+]
+
+[[package]]
+name = "rand_chacha"
+version = "0.3.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "e12735cf05c9e10bf21534da50a147b924d555dc7a547c42e6bb2d5b6017ae0d"
+dependencies = [
+ "ppv-lite86",
+ "rand_core 0.6.0",
 ]
 
 [[package]]
@@ -1162,7 +1195,16 @@ version = "0.5.1"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "90bde5296fc891b0cef12a6d03ddccc162ce7b2aff54160af9338f8d40df6d19"
 dependencies = [
- "getrandom",
+ "getrandom 0.1.15",
+]
+
+[[package]]
+name = "rand_core"
+version = "0.6.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "a8b34ba8cfb21243bd8df91854c830ff0d785fff2e82ebd4434c2644cb9ada18"
+dependencies = [
+ "getrandom 0.2.0",
 ]
 
 [[package]]
@@ -1171,7 +1213,16 @@ version = "0.2.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "ca3129af7b92a17112d59ad498c6f81eaf463253766b90396d39ea7a39d6613c"
 dependencies = [
- "rand_core",
+ "rand_core 0.5.1",
+]
+
+[[package]]
+name = "rand_hc"
+version = "0.3.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "3190ef7066a446f2e7f42e239d161e905420ccab01eb967c9eb27d21b2322a73"
+dependencies = [
+ "rand_core 0.6.0",
 ]
 
 [[package]]
@@ -1427,7 +1478,7 @@ source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "84db25042349bccfed0c40513ba3ee3522aeebef4f6c398fcc56e123e6e5c665"
 dependencies = [
  "crypto2",
- "rand",
+ "rand 0.7.3",
  "ring",
 ]
 
@@ -1478,7 +1529,7 @@ dependencies = [
  "nix",
  "pin-project 1.0.2",
  "qrcode",
- "rand",
+ "rand 0.8.0",
  "regex",
  "rustls-native-certs",
  "serde",
@@ -1605,7 +1656,7 @@ checksum = "7a6e24d9338a0a5be79593e2fa15a648add6138caa803e2d5bc782c371732ca9"
 dependencies = [
  "cfg-if 0.1.10",
  "libc",
- "rand",
+ "rand 0.7.3",
  "redox_syscall",
  "remove_dir_all",
  "winapi",
@@ -1862,7 +1913,7 @@ dependencies = [
  "ipnet",
  "lazy_static",
  "log",
- "rand",
+ "rand 0.7.3",
  "serde",
  "smallvec",
  "thiserror",
diff --git a/crates/shadowsocks-service/Cargo.toml b/crates/shadowsocks-service/Cargo.toml
index b0134aa6a34b..cf07c8152660 100644
--- a/crates/shadowsocks-service/Cargo.toml
+++ b/crates/shadowsocks-service/Cargo.toml
@@ -75,7 +75,7 @@ lru_time_cache = "0.11"
 bytes = "0.6"
 byte_string = "1.0"
 byteorder = "1.3"
-rand = { version = "0.7", optional = true }
+rand = { version = "0.8", optional = true }
 
 futures = "0.3"
 tokio = { version = "0.3.1", features = ["full"] }
diff --git a/crates/shadowsocks-service/src/local/dns/server.rs b/crates/shadowsocks-service/src/local/dns/server.rs
index 053e7f80bb17..3e7df2de53a8 100644
--- a/crates/shadowsocks-service/src/local/dns/server.rs
+++ b/crates/shadowsocks-service/src/local/dns/server.rs
@@ -639,7 +639,7 @@ impl DnsClient {
                     // Then this future will be disabled and have no effect
                     //
                     // Randomly choose from 500ms ~ 1.5s for preventing obvious request pattern
-                    let sleep_time = thread_rng().gen_range(500, 1500);
+                    let sleep_time = thread_rng().gen_range(500..=1500);
                     time::sleep(Duration::from_millis(sleep_time)).await;
 
                     let server = self.balancer.best_tcp_server();