diff --git a/cg_init_machine.sh b/cg_init_machine.sh
index fc74d45..0075c6b 100644
--- a/cg_init_machine.sh
+++ b/cg_init_machine.sh
@@ -18,12 +18,8 @@ END
 
 getent group wheel || groupadd wheel
 useradd cg_maintain_user
-if command -v groupmems &> /dev/null
-then
-    groupmems -g wheel -a cg_maintain_user
-else
-    usermod -a -G wheel cg_maintain_user
-fi
+usermod -a -G wheel cg_maintain_user
+
 echo '%wheel ALL=(ALL:ALL) NOPASSWD:    ALL' | EDITOR='tee -a' visudo
 mkdir -p /home/cg_maintain_user/.ssh
 res="$(python3 -c "$GET_KEY_CODE")"
@@ -31,15 +27,21 @@ echo "$res" >/home/cg_maintain_user/.ssh/authorized_keys
 chown -R cg_maintain_user:cg_maintain_user /home/cg_maintain_user
 chmod 600 /home/cg_maintain_user/.ssh/authorized_keys
 
-if command -v yum &> /dev/null
+if command -v yum >/dev/null >/dev/null 2>&1
 then
-    yum install -y net-snmp
+    sudo yum install -y net-snmp
 else
-    apt-get install -y snmpd
+    sudo apt-get install -y snmpd
 fi
 
 sudo cp /etc/snmp/snmpd.conf /etc/snmp/snmpd.bak
 sudo curl -L -o /etc/snmp/snmpd.conf https://git.tobyliu.com/toby/common-tools/raw/branch/main/snmpd.conf
 sudo systemctl restart snmpd
-sudo firewall-cmd --zone=public --add-service=snmp --permanent
-sudo firewall-cmd --reload
+
+if command -v firewall-cmd >/dev/null >/dev/null 2>&1
+then
+    sudo firewall-cmd --zone=public --add-service=snmp --permanent
+    sudo firewall-cmd --reload
+else
+    sudo ufw allow from any to any port 161
+fi