diff --git a/install_nginx.sh b/install_nginx.sh
index 7f618e9..b1efdaa 100644
--- a/install_nginx.sh
+++ b/install_nginx.sh
@@ -1,4 +1,32 @@
 #!/bin/bash
+vercomp () {
+    if [[ "$1" == "$2" ]]; then
+        echo "=";
+        return 0;
+    fi
+    local IFS=.;
+    local i ver1=($1) ver2=($2);
+    # fill empty fields in ver1 with zeros
+    for ((i=${#ver1[@]}; i<${#ver2[@]}; i++)); do
+        ver1[i]=0
+    done
+    for ((i=0; i<${#ver1[@]}; i++)); do
+        if [[ -z ${ver2[i]} ]]; then
+            # fill empty fields in ver2 with zeros
+            ver2[i]=0
+        fi
+        if ((10#${ver1[i]} > 10#${ver2[i]})); then
+            echo ">";
+            return 0;
+        fi
+        if ((10#${ver1[i]} < 10#${ver2[i]})); then
+            echo "<";
+            return 0;
+        fi
+    done
+    echo "=";
+    return 0;
+}
 function escape_str(){
     echo $1|sed -E 's/\\+//g' |sed -E 's/[\/\.\*]/\\\0/g'
 }
@@ -25,7 +53,7 @@ force_reinstall_openssl="0"
 if [[ ! -d "/usr/include/openssl" ]] && [[ ! -d "/usr/local/include/openssl" ]] && [[ ! -d "/usr/pkg/include/openssl" ]] && [[ ! -d "/opt/local/include/openssl" ]] && [[ ! -d /opt/openssl/include/openssl ]]; then
     force_reinstall_openssl="1"
 fi
-if [[ "$openssl_ver" < "1.1.1" ]] || [[ "$force_reinstall_openssl" == "1" ]]; then
+if [[ $(vercomp "$openssl_ver" "1.1.1") == "<" ]] || [[ "$force_reinstall_openssl" == "1" ]]; then
     # Build openssl
     target_openssl_ver="1.1.1q"
     sudo bash -l -c "
@@ -48,7 +76,7 @@ fi
 if [ -z "$cpu_cores" ]; then
     cpu_cores="1";
 fi
-if [[ "$ubuntu_ver" < "16" ]]; then #Need update ca-certificates manual
+if [[ $(vercomp "$ubuntu_ver" "16") == "<" ]]; then #Need update ca-certificates manual
     sudo bash -l -c "
         cd /root &&
         wget https://launchpad.net/ubuntu/+archive/primary/+sourcefiles/ca-certificates/20210119~20.04.2/ca-certificates_20210119~20.04.2.tar.xz --no-check-certificate -O ca-certificates_20210119~20.04.2.tar.xz &&
@@ -56,6 +84,8 @@ if [[ "$ubuntu_ver" < "16" ]]; then #Need update ca-certificates manual
         cd ca-certificates-20210119~20.04.1 &&
         make -j$cpu_cores && make install &&
         dpkg-reconfigure -fnoninteractive ca-certificates &&
+        if [ -e /etc/ca-certificates.conf ]; then sed -E 's/^!//g' -i /etc/ca-certificates.conf; fi &&
+        dpkg-reconfigure -fnoninteractive ca-certificates &&
         update-ca-certificates --fresh --verbose &&
         /usr/bin/c_rehash /etc/ssl/certs"
     cd "$org_pwd"
@@ -74,7 +104,7 @@ extra_remove_packages=""
 extra_build_nginx_cmd="true"
 if [[ "$@" == *"--install-modsecurity"* ]];then
     install_modsecurity="1"
-    if [[ "$ubuntu_ver" < "16" ]]; then #use 3.0.6
+    if [[ $(vercomp "$ubuntu_ver" "16") == "<" ]]; then #use 3.0.6
         sudo bash -l -c "
             cd /root &&
             apt-get install -y apt-utils autoconf automake build-essential git libcurl4-openssl-dev libgeoip-dev liblmdb-dev libpcre++-dev libtool libxml2-dev libyajl-dev pkgconf wget zlib1g-dev &&
@@ -160,7 +190,7 @@ if [[ ! -f /etc/init.d/nginx ]]; then
     sudo wget http://gitlab.tp.rulingcom.com/erictyl/install_r45_on_ubuntu_1804lts_doc/-/raw/master/nginx_service.sh -O /etc/init.d/nginx
     sudo chmod 755 /etc/init.d/nginx
     sudo chown root:root /etc/init.d/nginx
-    if [[ "$ubuntu_ver" > "16" ]] || [[ "$ubuntu_ver" == "16" ]]; then
+    if [[ $(vercomp "$ubuntu_ver" "16") == ">" ]]; then
         sudo wget http://gitlab.tp.rulingcom.com/erictyl/install_r45_on_ubuntu_1804lts_doc/-/raw/master/nginx.service -O /lib/systemd/system/nginx.service
         sudo chown root:root /lib/systemd/system/nginx.service
         sudo chmod 644 /lib/systemd/system/nginx.service
@@ -171,7 +201,7 @@ if [[ ! -f /etc/init.d/nginx ]]; then
     fi
 fi
 nginx_target_ver="1.23.1"
-if [[ "$nginx_ver" < $nginx_target_ver ]] || [[ "$1" == '--force' ]] || [[ "$install_modsecurity" == "1" ]] || [[ "$install_passenger" == "1" ]]; then
+if [[ $(vercomp "$nginx_ver" "$nginx_target_ver") ==  "<"]] || [[ "$1" == '--force' ]] || [[ "$install_modsecurity" == "1" ]] || [[ "$install_passenger" == "1" ]]; then
     if [ -f "/etc/nginx/nginx.conf" ]; then
         nginx_conf_exist="1"
     else