diff --git a/Install-preparations.md b/Install-preparations.md
index db30c39..37e023c 100644
--- a/Install-preparations.md
+++ b/Install-preparations.md
@@ -4,7 +4,7 @@
 apt-get install openssl cron  netcat-openbsd  curl
 ```
 
-Either `netcat` or `netcat-openbsd` is working.
+Or install `netcat`.
 ```
 apt-get install netcat
 ```
@@ -13,12 +13,16 @@ apt-get install netcat
 # 2. CentOS
 
 ```
-yum -q -y install  openssl  crontabs  nc  curl
+yum -q -y install  openssl  crontabs  netcat-openbsd curl
 ```
 For centos 5:
 
 ```
-yum -q -y install openssl,vixie-cron,nc,curl
+yum -q -y install openssl vixie-cron netcat-openbsd curl
 ```
 
+Or install `nc`
+```
+yum -q -y install nc
+```