# Firewall Best Practices for Securing Smart Healthcare Environment: A Review
## 3 Firewalls Types for Smart Healthcare Environment  
Firewalls today represent the first line of defense against major attacks, affecting both traditional and modern networks, and enforcing the protection of inside networks from external (and untrusted) networks. The application of an effective set of security practices and policies may indeed keep those systems safe and save entire businesses. Firewalls have a very important function of protecting, filtering, and controlling all traffic sent and received from the computer, Local Area Network (LAN), or Wide Local Area Network (WLAN) internal networks from unauthorized intrusions or external attacks [22]. Firewalls can either be hardware or device software, and filter and control information coming from the internet to one's private network or individual computer. They can also filter and control information coming out from the smart healthcare networks to the internet. Firewalls allow the transit in and/or out only to the data considered safe and harmless. Data are allowed through a series of internet protocols (TCP/IP, UDP, ICMP, etc. ), in which each computer is identified with an IP address. These data are also called \"data packets\", and these packets have the following headers that identify them:  
* IP address of the packet sender;
* IP address of the packet receiver;
* Packet type (TCP/IP, UDP, etc. );
* Port number (port is a number related to a service/network application). The standard allowed ports are typically 21/FTP, 22/SSH, 23/TELNET, 80/HTTP, and 443/HTTPS. Usually, a received packet is matched against a certain rule previously set; this can be discarded or forwarded depending on what this rule establishes. This function introduces the first and basic firewall category, packet filtering. This method allows dynamically generating packet filter rules, showing a certain expiration time instead of being static (or stateless), which is the stateful inspection firewalls. Regarding the smart healthcare environment, the selection of a firewall with an appropriate configuration of rules effectively reduces the impact of attack [23]. We can have hardware firewalls, which are physical devices used to protect local networks, and are normally integrated into TCP/IP routers or software firewalls, applicable to public networks using a central computer installingfirewall software. Firewalls act as a filter on IP address, packet attributes, or a connection state basis, according to the Open Systems Interconnection (OSI) layer classification. Figure 2 presents the broader classification of various protocols and firewall types, which are arranged according to the OSI reference model [24]. Moreover, the firewalls are often grouped into network firewalls and host-based firewalls [25]: the former generally run on dedicated hardware and can handle data from (and to) a large number of servers on one or multiple networks. The latter are configured directly on a host or cloud server, limiting themselves to controlling the traffic generated and delivered to the machine. Granting access to multiple developments, pre-production, and production environments, in which, through automatic systems and pipelines, code, and configurations through fast and streamlined processes, requires smarter and effective firewall rules. This first classification helps to introduce some useful characteristics to distinguish traditional firewall types from cloud firewall ones. The firewall types and their specific categories are given in Figure 3.  
Figure 3: Taxonomy diagram of firewalls (micro categories). Figure 2: Firewall practice and level of controls according to the OSI reference model. There is growing demand for smart healthcare leveraging cloud-based computing and cloud services that offer an array of benefits in compression to in-house network systems. Moreover, the use of cloud-based firewalls reduces operational cost and influences more economic benefits. Furthermore, cloud-based firewalls for healthcare systems provide better security and privacy for health data and systems [26].