application layer firewall in a sentence

1. Typically it works as an application layer firewall.
2. Along with Sidewinder, Gauntlet had been one of the earliest application layer firewalls; both had developed a large customer base in the United States Department of Defense.
3. When a port forward is implemented by a proxy process ( such as on application layer firewalls, SOCKS based firewalls, or via TCP circuit proxies ), then no packets are actually translated, only data is proxied.
4. It's difficult to find application layer firewall in a sentence.