To install Steam on a barebone Centos7 follow the next console commands:

yum install glibc.i686 libstdc++.i686 libgcc.i686
iptables -I INPUT -p udp –dport 27016 -j ACCEPT
iptables -I INPUT -p tcp –dport 27016 -j ACCEPT
iptables -I INPUT -p udp –dport 7778 -j ACCEPT
iptables -I INPUT -p tcp –dport 7778 -j ACCEPT
iptables -I INPUT -p tcp –dport 32330 -j ACCEPT

useradd -m steam
su – steam

mkdir steamcmd
cd steamcmd
wget http://media.steampowered.com/installer/steamcmd_linux.tar.gz
tar -xvzf steamcmd_linux.tar.gz

./steamcmd.sh