diff --git a/.github/workflows/coverage.yml b/.github/workflows/coverage.yml
index 955f16a6b..b93c5f276 100644
--- a/.github/workflows/coverage.yml
+++ b/.github/workflows/coverage.yml
@@ -32,11 +32,12 @@ jobs:
 
       - name: Get dependencies
         if: steps.cache-gomodules.outputs.cache-hit != 'true'
-        run: |
-          go get -v -t -d ./...
+        run: go get -v -t -d ./...
 
       - name: Run coverage
-        run: ./testing/coverage/coverall2
+        run: |
+          chmod u+x ./testing/coverage/coverall.sh
+          ./testing/coverage/coverall.sh
 
       - name: Upload coverage to Codecov
         uses: codecov/codecov-action@v1
diff --git a/.github/workflows/release.yml b/.github/workflows/release.yml
index 9cfacd8ed..f83857c82 100644
--- a/.github/workflows/release.yml
+++ b/.github/workflows/release.yml
@@ -107,6 +107,7 @@ jobs:
       - name: Build Windows wv2ray
         if: matrix.goos == 'windows'
         run: |
+          echo "::warning ::wv2ray.exe will be removed in v5"
           go build -v -o build_assets/wv2ray.exe -trimpath -ldflags "-s -w -H windowsgui -buildid=" ./main
           cd ./build_assets || exit 1
           mv v2ray v2ray.exe
diff --git a/release/mutilate/removeVSign.sh b/release/mutilate/removeVSign.sh
deleted file mode 100755
index aec2cbe23..000000000
--- a/release/mutilate/removeVSign.sh
+++ /dev/null
@@ -1,7 +0,0 @@
-#!/usr/bin/env bash
-
-export VROOT=$(dirname "${BASH_SOURCE[0]}")/../../
-
-rm $VROOT/infra/control/verify.go
-
-sed -i '/VSign/d' $VROOT/go.mod
diff --git a/testing/coverage/coverall b/testing/coverage/coverall
deleted file mode 100755
index f9ac6db1f..000000000
--- a/testing/coverage/coverall
+++ /dev/null
@@ -1,48 +0,0 @@
-#!/bin/bash
-
-FAIL=0
-
-V2RAY_OUT=${PWD}/out/v2ray
-export V2RAY_COV=${V2RAY_OUT}/cov
-COVERAGE_FILE=${V2RAY_COV}/coverage.txt
-
-function test_package {
-  DIR=".$1"
-  DEP=$(go list -f '{{ join .Deps "\n" }}' $DIR | grep v2ray | tr '\n' ',')
-  DEP=${DEP}$DIR
-  RND_NAME=$(openssl rand -hex 16)
-  COV_PROFILE=${V2RAY_COV}/${RND_NAME}.out
-  go test -tags "json coverage" -coverprofile=${COV_PROFILE} -coverpkg=$DEP $DIR || FAIL=1
-}
-
-rm -rf ${V2RAY_OUT}
-mkdir -p ${V2RAY_COV}
-touch ${COVERAGE_FILE}
-
-TEST_FILES=(./*_test.go)
-if [ -f ${TEST_FILES[0]} ]; then
-  test_package ""
-fi
-
-for DIR in $(find * -type d ! -path "*.git*" ! -path "*vendor*" ! -path "*external*"); do
-  TEST_FILES=($DIR/*_test.go)
-  if [ -f ${TEST_FILES[0]} ]; then
-    test_package "/$DIR"
-  fi
-done
-
-for OUT_FILE in $(find ${V2RAY_COV} -name "*.out"); do
-  echo "Merging file ${OUT_FILE}"
-  cat ${OUT_FILE} | grep -v "mode: set" >> ${COVERAGE_FILE}
-done
-
-COV_SORTED=${V2RAY_COV}/coverallsorted.out
-cat ${COVERAGE_FILE} | sort -t: -k1 | grep -vw "testing" | grep -v ".pb.go" | grep -vw "vendor" | grep -vw "external" > ${COV_SORTED}
-echo "mode: set" | cat - ${COV_SORTED} > ${COVERAGE_FILE}
-
-if [ "$FAIL" -eq 0 ]; then
-  echo "Uploading coverage datea to codecov."
-  #bash <(curl -s https://codecov.io/bash) -f ${COVERAGE_FILE} -v || echo "Codecov did not collect coverage reports."
-fi
-
-exit $FAIL
diff --git a/testing/coverage/coverall2 b/testing/coverage/coverall.sh
similarity index 81%
rename from testing/coverage/coverall2
rename to testing/coverage/coverall.sh
index 8491ea5b5..d260e0cb5 100755
--- a/testing/coverage/coverall2
+++ b/testing/coverage/coverall.sh
@@ -1,4 +1,4 @@
-#!/bin/bash
+#!/usr/bin/env bash
 
 COVERAGE_FILE=${PWD}/coverage.txt
 COV_SORTED=${PWD}/coverallsorted.out
@@ -19,8 +19,7 @@ if [ -f "${TEST_FILES[0]}" ]; then
   test_package ""
 fi
 
-# shellcheck disable=SC2044
-for DIR in $(find ./* -type d ! -path "*.git*" ! -path "*vendor*" ! -path "*external*"); do
+for DIR in $(find ./* -type d ! -path "*.git*"); do
   TEST_FILES=("$DIR"/*_test.go)
   if [ -f "${TEST_FILES[0]}" ]; then
     test_package "/$DIR"
@@ -34,7 +33,7 @@ do
   < "${OUT_FILE}" grep -v "mode: set" >> "$COVERAGE_FILE"
 done <   <(find ./* -name "*.out" -print0)
 
-< "$COVERAGE_FILE" sort -t: -k1 | grep -vw "testing" | grep -v ".pb.go" | grep -vw "vendor" | grep -vw "external" > "$COV_SORTED"
+< "$COVERAGE_FILE" sort -t: -k1 | grep -vw "testing" | grep -v ".pb.go" > "$COV_SORTED"
 echo "mode: set" | cat - "${COV_SORTED}" > "${COVERAGE_FILE}"
 
-bash <(curl -s https://codecov.io/bash) || echo 'Codecov failed to upload'
\ No newline at end of file
+bash <(curl -s https://codecov.io/bash) || echo 'Codecov failed to upload'
diff --git a/testing/servers/tcp/port.go b/testing/servers/tcp/port.go
index cf4729d2c..86e73e7ac 100644
--- a/testing/servers/tcp/port.go
+++ b/testing/servers/tcp/port.go
@@ -1,16 +1,20 @@
 package tcp
 
-import (
-	"v2ray.com/core/common"
-	"v2ray.com/core/common/net"
-)
+import "v2ray.com/core/common/net"
 
-// PickPort returns an unused TCP port in the system. The port returned is highly likely to be unused, but not guaranteed.
+// PickPort returns an unused TCP port of the system.
 func PickPort() net.Port {
-	listener, err := net.Listen("tcp4", "127.0.0.1:0")
-	common.Must(err)
+	listener := pickPort()
 	defer listener.Close()
 
 	addr := listener.Addr().(*net.TCPAddr)
 	return net.Port(addr.Port)
 }
+
+func pickPort() net.Listener {
+	listener, err := net.Listen("tcp4", "127.0.0.1:0")
+	if err != nil {
+		listener = pickPort()
+	}
+	return listener
+}
diff --git a/testing/servers/udp/port.go b/testing/servers/udp/port.go
index 75da5df44..f71b0c96b 100644
--- a/testing/servers/udp/port.go
+++ b/testing/servers/udp/port.go
@@ -1,19 +1,23 @@
 package udp
 
-import (
-	"v2ray.com/core/common"
-	"v2ray.com/core/common/net"
-)
+import "v2ray.com/core/common/net"
 
-// PickPort returns an unused UDP port in the system. The port returned is highly likely to be unused, but not guaranteed.
+// PickPort returns an unused UDP port of the system.
 func PickPort() net.Port {
-	conn, err := net.ListenUDP("udp4", &net.UDPAddr{
-		IP:   net.LocalHostIP.IP(),
-		Port: 0,
-	})
-	common.Must(err)
+	conn := pickPort()
 	defer conn.Close()
 
 	addr := conn.LocalAddr().(*net.UDPAddr)
 	return net.Port(addr.Port)
 }
+
+func pickPort() *net.UDPConn {
+	conn, err := net.ListenUDP("udp4", &net.UDPAddr{
+		IP:   net.LocalHostIP.IP(),
+		Port: 0,
+	})
+	if err != nil {
+		conn = pickPort()
+	}
+	return conn
+}
diff --git a/transport/internet/sockopt_linux.go b/transport/internet/sockopt_linux.go
index 9c1c8f310..18471f8a6 100644
--- a/transport/internet/sockopt_linux.go
+++ b/transport/internet/sockopt_linux.go
@@ -9,9 +9,9 @@ import (
 
 const (
 	// For incoming connections.
-	TCP_FASTOPEN = 23
+	TCP_FASTOPEN = 23 // nolint: golint,stylecheck
 	// For out-going connections.
-	TCP_FASTOPEN_CONNECT = 30
+	TCP_FASTOPEN_CONNECT = 30 // nolint: golint,stylecheck
 )
 
 func bindAddr(fd uintptr, ip []byte, port uint32) error {
diff --git a/transport/internet/sockopt_windows.go b/transport/internet/sockopt_windows.go
index cb6292bca..f84900892 100644
--- a/transport/internet/sockopt_windows.go
+++ b/transport/internet/sockopt_windows.go
@@ -1,11 +1,9 @@
 package internet
 
-import (
-	"syscall"
-)
+import "syscall"
 
 const (
-	TCP_FASTOPEN = 15
+	TCP_FASTOPEN = 15 // nolint: golint,stylecheck
 )
 
 func setTFO(fd syscall.Handle, settings SocketConfig_TCPFastOpenState) error {