Obviously all possible care should be taken to insure that the firewall is as impenetrable as possible. This means that the personnel operating it should have the necessary equipment, software, training and personal skills to be successful. Because the firewall produces logs that may indicate attack signatures, the operators must be given time to examine the logs and the authority to follow any signs of a real attack. It's possible this may entail getting legal advice on the proper method of gathering data to support espionage charges and contacting law enforcement officials to press charges against intruders. Even a well-constructed and properly operated firewall can't protect against some types of attacks, especially those where the attacker has the ability to sniff the connections to the network under attack.
Some sites carefully allow the connection only for the limited duration of the actual session.
The second thing is to make sure that the password used during the session is not susceptible to sniffers. Sniffers are capable of picking up IP packets as they travel over networks. When used by legitimate network administrators, the sniffer is a powerful tool for diagnosing and solving problems. On the other hand, it can be misused with equally powerful results. The most common misuse of sniffers is to capture passwords from telnet or FTP or popmail login sessions.