Dear sir,
I read your job description very carefully.
As Senior Linux Administrator and Security Expert, I have a powerful skills in System Administration and Network Security.
In the past I have developed a lot of patch version of security package such as iptables/ipset, openvpn, snort and mod_security(web firewall).
Your job is an ideal match for my skills and experiences.
Thank you, Looking forward to hearing from you soon.
Best regards, TaeSung.