refactor: seperate application into seperate files and add killForwarding

ssh.go

@@ -0,0 +1,18 @@
+package main
+
+import "golang.org/x/crypto/ssh"
+
+type SSHConnection struct {
+	client  *ssh.Client
+	session *ssh.Session
+}
+
+func (s *SSHConnection) Close() {
+	if s.session != nil {
+		s.session.Close()
+	}
+
+	if s.client != nil {
+		s.client.Close()
+	}
+}