{"id":6519,"date":"2019-09-18T00:45:36","date_gmt":"2019-09-17T23:45:36","guid":{"rendered":"https:\/\/www.n-able.com\/?p=6519"},"modified":"2025-06-25T15:34:46","modified_gmt":"2025-06-25T14:34:46","slug":"how-do-firewalls-work","status":"publish","type":"post","link":"https:\/\/www.n-able.com\/de\/blog\/how-do-firewalls-work","title":{"rendered":"How Do Firewalls Work?"},"content":{"rendered":"<p>Cyberattacks can be incredibly devastating for businesses, not to mention costly\u2014it\u2019s estimated that in 2017, the cost of\u00a0<a class=\"ext\" href=\"https:\/\/www.cnbc.com\/2018\/02\/22\/cybercrime-pandemic-may-have-cost-the-world-600-billion-last-year.html\" target=\"_blank\" rel=\"noopener noreferrer\">cybercrime was nearly $600 billion<\/a>. With the number of targeted cyberattacks continuing to rise,\u00a0<a href=\"https:\/\/www.solarwindsmsp.com\/products\/use-cases\/msp-security-software\">managed services providers (MSPs) are under increased pressure\u00a0<\/a>to secure customer networks from threats.<\/p>\n<p>As an MSP, you know that having a firewall (or multiple firewalls, for that matter) can make a big difference in network security. Firewalls help protect networks and devices from a wide range of security risks, namely unauthorized access from outside your customers\u2019 networks. They can also inform you of potentially threatening attempts to connect from within customer networks.<\/p>\n<p>Knowing how to properly articulate the role of firewalls for your customers is a key part of delivering service as an MSP. If you\u2019ve ever had a customer ask \u201cWhat does a firewall do?\u201d or \u201cHow do firewalls work?\u201d this guide can help walk you through simple ways to explain these concepts.<\/p>\n<h3><b>Firewalls explained<\/b><\/h3>\n<p>Firewalls are software or hardware that work as a filtration system for the data attempting to enter your computer or network.\u00a0<a href=\"https:\/\/www.n-able.com\/blog\/malware-analysis-steps\">Firewalls scan packets for malicious code<\/a>\u00a0or attack vectors that have already been identified as established threats. Should a data packet be flagged and determined to be a security risk, the<b>\u00a0<\/b>firewall prevents it from entering the network or reaching your computer.<\/p>\n<p>There are several different ways security firewalls can monitor and regulate network traffic. These methods can include:<\/p>\n<ul>\n<li><b>Packet filtering.<\/b>\u00a0Packets are small amounts of data. When a firewall uses packet filtering, the packets attempting to enter the network are run against a group of filters. These filters remove the packets that match certain identified threats and allow the others through to their intended destination.<\/li>\n<li><b>Proxy service.<\/b>\u00a0These firewalls are incredibly secure, but they come with their own drawbacks. They work more slowly than other types of firewalls and are often limited with regard to the sorts of applications they can support. Instead of serving as a filtration system that data passes through, <a href=\"https:\/\/www.n-able.com\/cyber-encyclopedia\/what-is-a-proxy-server\"  data-wpil-monitor-id=\"44\">proxy servers<\/a> function as go-betweens. By essentially creating a mirror of the computer behind the firewall, they prevent direct connections between the customer device and the incoming packets, protecting your network location from potential bad actors.<\/li>\n<li><b>Stateful inspection.<\/b>\u00a0Where static filtering examines the packet headers, stateful inspection firewalls examine a variety of elements of each data packet and compare them to a database of trusted information. These elements include source and destination IP addresses, ports, and applications. Incoming data packets are required to sufficiently match the trusted information in order to be allowed through the firewall. Stateful inspection is a newer method of firewall filtering.<\/li>\n<\/ul>\n<h3><b>How does a firewall protect data?<\/b><\/h3>\n<p>By putting protective filters in place around your network and devices, firewalls can help to prevent a number of different security risks. These can include:<\/p>\n<ul>\n<li><b>Backdoors.<\/b>\u00a0While certain applications are designed to be accessed remotely, others may have bugs that give potential hackers a \u201cbackdoor,\u201d or a hidden way to access and exploit the program for malicious purposes. Some operating systems may also contain bugs that provide backdoors for skilled hackers to manipulate to their own benefit.<\/li>\n<li><b>Denial of service.<\/b>\u00a0This increasingly popular type of cyberattack can slow or crash a server. Hackers utilize this method by requesting to connect to the server, which sends an acknowledgment and attempts to establish a connection. However, as part of the attack, the server will not be able to locate the system that initiated the request. Flooding a server with these one-sided session requests allows a hacker to slow down server performance or take it offline entirely. While there are ways firewalls can be used to identify and protect against certain forms of denial of service attacks, they tend to be easily fooled and are usually ineffective. For this reason, it\u2019s important to have a variety of security measures in place to protect your network from different types of attacks.<\/li>\n<li><b>Macros.<\/b>\u00a0Macros are scripts that applications can run to streamline a series of complicated procedures into one executable rule. Should a hacker gain access to your customers\u2019 devices, they can run their own macros within the applications. This can have drastic effects, ranging from data loss to system failure. These executable fragments can also be embedded data attempting to enter your network, which firewalls can help identify and discard.<\/li>\n<li><b>Remote logins.<\/b>\u00a0Remote logins can vary in severity, but always refer to someone connecting to and controlling your computer. They can be a useful technique for allowing IT professionals to quickly update something on a specific device without being physically present\u2014but if performed by bad actors, they can be used to access sensitive files or even execute unwanted programs.<\/li>\n<li><b>Spam.<\/b>\u00a0While most spam is harmless, some spam can also be incredibly malicious. Spam often will include links\u2014which should absolutely never be clicked! By following links in spam mail, users may accept cookies onto their systems that create backdoor functionality for hackers. It is important that your customers receive\u00a0<a href=\"https:\/\/www.n-able.com\/blog\/6-most-effective-tactics-to-protect-your-business-from-malware-in-2020\">cybersecurity awareness training<\/a>\u00a0in order to reduce vulnerabilities from within their network.<\/li>\n<li><b>Viruses.<\/b>\u00a0Viruses are small programs that replicate themselves from computer to computer, allowing them to spread between devices and across networks. The threat posed by some viruses can be relatively small, but others are capable of doing more damage\u2014such as erasing your customers\u2019 data. Some firewalls include virus protection, but using a firewall alongside antivirus software is a smarter and more secure choice.<\/li>\n<\/ul>\n<p>Because there are so many varieties of potential cyberattacks, it can be difficult for firewalls to filter out every threat. While firewalls are extremely beneficial in securing networks, it is essential to also pair firewalls with other security programs and hardware as part of a robust security lineup.<\/p>\n<h3><b>How does a multilayer firewall work?<\/b><\/h3>\n<p>Multilayer firewalls function like packet-scanning firewalls in that they filter out incoming data before it can actually enter the network. The difference is that multilayer firewalls use what is called \u201cdynamic packet filtering,\u201d which involves monitoring the networks\u2019 active connections. Based on those connections, the firewall will assess which packets are safe and can be allowed through. Multilayer firewalls offer a number of benefits in securing networks, but can be expensive to employ.<\/p>\n<h3><b>How do I use a firewall?<\/b><\/h3>\n<p>There are both hardware and\u00a0<a href=\"https:\/\/www.solarwindsmsp.com\/products\/n-central\/use-cases\/firewall-management-software\">software firewalls<\/a>. The hardware options are often built in to routers to intercept traffic moving between the broadband router and user devices. Software options are programs that monitor the traffic going in and out of your computer. If you are running a Windows operating system, there is a built-in software firewall that you can access by opening the Control Panel and clicking the Windows Firewall pane.<\/p>\n<p><b>Interested in learning more about how firewalls work?\u00a0<a href=\"https:\/\/www.n-able.com\/blog\">Read through our blog<\/a>\u00a0for other common questions and concerns with firewalls.<\/b><\/p>\n<p>&nbsp;<\/p>\n","protected":false},"excerpt":{"rendered":"<p>Cyberattacks can be incredibly devastating for businesses, not to mention costly\u2014it\u2019s estimated that in 2017, the cost of\u00a0cybercrime was nearly $600 billion. With the number of targeted cyberattacks continuing to&#8230;<\/p>\n","protected":false},"author":24,"featured_media":0,"comment_status":"closed","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"_acf_changed":false,"inline_featured_image":false,"footnotes":""},"class_list":["post-6519","post","type-post","status-publish","format-standard","hentry","topic-security"],"acf":[],"yoast_head":"<!-- This site is optimized with the Yoast SEO Premium plugin v27.2 (Yoast SEO v27.2) - https:\/\/yoast.com\/product\/yoast-seo-premium-wordpress\/ -->\n<title>Security Firewalls: How Do Firewalls Work? - N-able<\/title>\n<meta name=\"description\" content=\"Read how network firewalls work and the importance of having security firewalls to protect your infrastructure.\" \/>\n<meta name=\"robots\" content=\"index, follow, max-snippet:-1, max-image-preview:large, max-video-preview:-1\" \/>\n<link rel=\"canonical\" href=\"https:\/\/www.n-able.com\/de\/blog\/how-do-firewalls-work\" \/>\n<meta property=\"og:locale\" content=\"de_DE\" \/>\n<meta property=\"og:type\" content=\"article\" \/>\n<meta property=\"og:title\" content=\"Security Firewalls: How Do Firewalls Work? - N-able\" \/>\n<meta property=\"og:description\" content=\"Read how network firewalls work and the importance of having security firewalls to protect your infrastructure.\" \/>\n<meta property=\"og:url\" content=\"https:\/\/www.n-able.com\/de\/blog\/how-do-firewalls-work\" \/>\n<meta property=\"og:site_name\" content=\"N-able\" \/>\n<meta property=\"article:publisher\" content=\"https:\/\/www.facebook.com\/NableMSP\" \/>\n<meta property=\"article:published_time\" content=\"2019-09-17T23:45:36+00:00\" \/>\n<meta property=\"article:modified_time\" content=\"2025-06-25T14:34:46+00:00\" \/>\n<meta property=\"og:image\" content=\"https:\/\/www.n-able.com\/wp-content\/uploads\/2021\/03\/share-image.jpg\" \/>\n\t<meta property=\"og:image:width\" content=\"1200\" \/>\n\t<meta property=\"og:image:height\" content=\"630\" \/>\n\t<meta property=\"og:image:type\" content=\"image\/jpeg\" \/>\n<meta name=\"author\" content=\"N-able\" \/>\n<meta name=\"twitter:card\" content=\"summary_large_image\" \/>\n<meta name=\"twitter:creator\" content=\"@Nable\" \/>\n<meta name=\"twitter:site\" content=\"@Nable\" \/>\n<meta name=\"twitter:label1\" content=\"Verfasst von\" \/>\n\t<meta name=\"twitter:data1\" content=\"N-able\" \/>\n\t<meta name=\"twitter:label2\" content=\"Gesch\u00e4tzte Lesezeit\" \/>\n\t<meta name=\"twitter:data2\" content=\"5\u00a0Minuten\" \/>\n<script type=\"application\/ld+json\" class=\"yoast-schema-graph\">{\"@context\":\"https:\/\/schema.org\",\"@graph\":[{\"@type\":\"Article\",\"@id\":\"https:\/\/www.n-able.com\/de\/blog\/how-do-firewalls-work#article\",\"isPartOf\":{\"@id\":\"https:\/\/www.n-able.com\/de\/blog\/how-do-firewalls-work\"},\"author\":{\"name\":\"N-able\",\"@id\":\"https:\/\/www.n-able.com\/de#\/schema\/person\/f46a000e389b6d02bd4b3866e7828a7b\"},\"headline\":\"How Do Firewalls Work?\",\"datePublished\":\"2019-09-18T00:45:36+01:00\",\"dateModified\":\"2025-06-25T14:34:46+00:00\",\"mainEntityOfPage\":{\"@id\":\"https:\/\/www.n-able.com\/de\/blog\/how-do-firewalls-work\"},\"wordCount\":1138,\"publisher\":{\"@id\":\"https:\/\/www.n-able.com\/de#organization\"},\"articleSection\":[\"Security\"],\"inLanguage\":\"de\"},{\"@type\":\"WebPage\",\"@id\":\"https:\/\/www.n-able.com\/de\/blog\/how-do-firewalls-work\",\"url\":\"https:\/\/www.n-able.com\/de\/blog\/how-do-firewalls-work\",\"name\":\"Security Firewalls: How Do Firewalls Work? - N-able\",\"isPartOf\":{\"@id\":\"https:\/\/www.n-able.com\/de#website\"},\"datePublished\":\"2019-09-18T00:45:36+01:00\",\"dateModified\":\"2025-06-25T14:34:46+00:00\",\"description\":\"Read how network firewalls work and the importance of having security firewalls to protect your infrastructure.\",\"breadcrumb\":{\"@id\":\"https:\/\/www.n-able.com\/de\/blog\/how-do-firewalls-work#breadcrumb\"},\"inLanguage\":\"de\",\"potentialAction\":[{\"@type\":\"ReadAction\",\"target\":[\"https:\/\/www.n-able.com\/de\/blog\/how-do-firewalls-work\"]}]},{\"@type\":\"BreadcrumbList\",\"@id\":\"https:\/\/www.n-able.com\/de\/blog\/how-do-firewalls-work#breadcrumb\",\"itemListElement\":[{\"@type\":\"ListItem\",\"position\":1,\"name\":\"Security\",\"item\":\"https:\/\/www.n-able.com\/de\/blog\/category\/security\"},{\"@type\":\"ListItem\",\"position\":2,\"name\":\"How Do Firewalls Work?\"}]},{\"@type\":\"WebSite\",\"@id\":\"https:\/\/www.n-able.com\/de#website\",\"url\":\"https:\/\/www.n-able.com\/de\",\"name\":\"N-able\",\"description\":\"\",\"publisher\":{\"@id\":\"https:\/\/www.n-able.com\/de#organization\"},\"potentialAction\":[{\"@type\":\"SearchAction\",\"target\":{\"@type\":\"EntryPoint\",\"urlTemplate\":\"https:\/\/www.n-able.com\/de?s={search_term_string}\"},\"query-input\":{\"@type\":\"PropertyValueSpecification\",\"valueRequired\":true,\"valueName\":\"search_term_string\"}}],\"inLanguage\":\"de\"},{\"@type\":\"Organization\",\"@id\":\"https:\/\/www.n-able.com\/de#organization\",\"name\":\"N-able\",\"url\":\"https:\/\/www.n-able.com\/de\",\"logo\":{\"@type\":\"ImageObject\",\"inLanguage\":\"de\",\"@id\":\"https:\/\/www.n-able.com\/de#\/schema\/logo\/image\/\",\"url\":\"https:\/\/www.n-able.com\/wp-content\/uploads\/2021\/02\/logo-n-able-vertical-dark.svg\",\"contentUrl\":\"https:\/\/www.n-able.com\/wp-content\/uploads\/2021\/02\/logo-n-able-vertical-dark.svg\",\"width\":\"1024\",\"height\":\"1024\",\"caption\":\"N-able\"},\"image\":{\"@id\":\"https:\/\/www.n-able.com\/de#\/schema\/logo\/image\/\"},\"sameAs\":[\"https:\/\/www.facebook.com\/NableMSP\",\"https:\/\/x.com\/Nable\",\"https:\/\/www.linkedin.com\/company\/n-able\",\"https:\/\/www.youtube.com\/channel\/UClnp77HHg4aME-S-3fWQhFw\"]},{\"@type\":\"Person\",\"@id\":\"https:\/\/www.n-able.com\/de#\/schema\/person\/f46a000e389b6d02bd4b3866e7828a7b\",\"name\":\"N-able\",\"image\":{\"@type\":\"ImageObject\",\"inLanguage\":\"de\",\"@id\":\"https:\/\/secure.gravatar.com\/avatar\/e9c468b7c98137ecdd5508befa660c205a7978133257080a37fb0b1362d53411?s=96&d=mm&r=g\",\"url\":\"https:\/\/secure.gravatar.com\/avatar\/e9c468b7c98137ecdd5508befa660c205a7978133257080a37fb0b1362d53411?s=96&d=mm&r=g\",\"contentUrl\":\"https:\/\/secure.gravatar.com\/avatar\/e9c468b7c98137ecdd5508befa660c205a7978133257080a37fb0b1362d53411?s=96&d=mm&r=g\",\"caption\":\"N-able\"}}]}<\/script>\n<!-- \/ Yoast SEO Premium plugin. -->","yoast_head_json":{"title":"Security Firewalls: How Do Firewalls Work? - N-able","description":"Read how network firewalls work and the importance of having security firewalls to protect your infrastructure.","robots":{"index":"index","follow":"follow","max-snippet":"max-snippet:-1","max-image-preview":"max-image-preview:large","max-video-preview":"max-video-preview:-1"},"canonical":"https:\/\/www.n-able.com\/de\/blog\/how-do-firewalls-work","og_locale":"de_DE","og_type":"article","og_title":"Security Firewalls: How Do Firewalls Work? - N-able","og_description":"Read how network firewalls work and the importance of having security firewalls to protect your infrastructure.","og_url":"https:\/\/www.n-able.com\/de\/blog\/how-do-firewalls-work","og_site_name":"N-able","article_publisher":"https:\/\/www.facebook.com\/NableMSP","article_published_time":"2019-09-17T23:45:36+00:00","article_modified_time":"2025-06-25T14:34:46+00:00","og_image":[{"width":1200,"height":630,"url":"https:\/\/www.n-able.com\/wp-content\/uploads\/2021\/03\/share-image.jpg","type":"image\/jpeg"}],"author":"N-able","twitter_card":"summary_large_image","twitter_creator":"@Nable","twitter_site":"@Nable","twitter_misc":{"Verfasst von":"N-able","Gesch\u00e4tzte Lesezeit":"5\u00a0Minuten"},"schema":{"@context":"https:\/\/schema.org","@graph":[{"@type":"Article","@id":"https:\/\/www.n-able.com\/de\/blog\/how-do-firewalls-work#article","isPartOf":{"@id":"https:\/\/www.n-able.com\/de\/blog\/how-do-firewalls-work"},"author":{"name":"N-able","@id":"https:\/\/www.n-able.com\/de#\/schema\/person\/f46a000e389b6d02bd4b3866e7828a7b"},"headline":"How Do Firewalls Work?","datePublished":"2019-09-18T00:45:36+01:00","dateModified":"2025-06-25T14:34:46+00:00","mainEntityOfPage":{"@id":"https:\/\/www.n-able.com\/de\/blog\/how-do-firewalls-work"},"wordCount":1138,"publisher":{"@id":"https:\/\/www.n-able.com\/de#organization"},"articleSection":["Security"],"inLanguage":"de"},{"@type":"WebPage","@id":"https:\/\/www.n-able.com\/de\/blog\/how-do-firewalls-work","url":"https:\/\/www.n-able.com\/de\/blog\/how-do-firewalls-work","name":"Security Firewalls: How Do Firewalls Work? - N-able","isPartOf":{"@id":"https:\/\/www.n-able.com\/de#website"},"datePublished":"2019-09-18T00:45:36+01:00","dateModified":"2025-06-25T14:34:46+00:00","description":"Read how network firewalls work and the importance of having security firewalls to protect your infrastructure.","breadcrumb":{"@id":"https:\/\/www.n-able.com\/de\/blog\/how-do-firewalls-work#breadcrumb"},"inLanguage":"de","potentialAction":[{"@type":"ReadAction","target":["https:\/\/www.n-able.com\/de\/blog\/how-do-firewalls-work"]}]},{"@type":"BreadcrumbList","@id":"https:\/\/www.n-able.com\/de\/blog\/how-do-firewalls-work#breadcrumb","itemListElement":[{"@type":"ListItem","position":1,"name":"Security","item":"https:\/\/www.n-able.com\/de\/blog\/category\/security"},{"@type":"ListItem","position":2,"name":"How Do Firewalls Work?"}]},{"@type":"WebSite","@id":"https:\/\/www.n-able.com\/de#website","url":"https:\/\/www.n-able.com\/de","name":"N-able","description":"","publisher":{"@id":"https:\/\/www.n-able.com\/de#organization"},"potentialAction":[{"@type":"SearchAction","target":{"@type":"EntryPoint","urlTemplate":"https:\/\/www.n-able.com\/de?s={search_term_string}"},"query-input":{"@type":"PropertyValueSpecification","valueRequired":true,"valueName":"search_term_string"}}],"inLanguage":"de"},{"@type":"Organization","@id":"https:\/\/www.n-able.com\/de#organization","name":"N-able","url":"https:\/\/www.n-able.com\/de","logo":{"@type":"ImageObject","inLanguage":"de","@id":"https:\/\/www.n-able.com\/de#\/schema\/logo\/image\/","url":"https:\/\/www.n-able.com\/wp-content\/uploads\/2021\/02\/logo-n-able-vertical-dark.svg","contentUrl":"https:\/\/www.n-able.com\/wp-content\/uploads\/2021\/02\/logo-n-able-vertical-dark.svg","width":"1024","height":"1024","caption":"N-able"},"image":{"@id":"https:\/\/www.n-able.com\/de#\/schema\/logo\/image\/"},"sameAs":["https:\/\/www.facebook.com\/NableMSP","https:\/\/x.com\/Nable","https:\/\/www.linkedin.com\/company\/n-able","https:\/\/www.youtube.com\/channel\/UClnp77HHg4aME-S-3fWQhFw"]},{"@type":"Person","@id":"https:\/\/www.n-able.com\/de#\/schema\/person\/f46a000e389b6d02bd4b3866e7828a7b","name":"N-able","image":{"@type":"ImageObject","inLanguage":"de","@id":"https:\/\/secure.gravatar.com\/avatar\/e9c468b7c98137ecdd5508befa660c205a7978133257080a37fb0b1362d53411?s=96&d=mm&r=g","url":"https:\/\/secure.gravatar.com\/avatar\/e9c468b7c98137ecdd5508befa660c205a7978133257080a37fb0b1362d53411?s=96&d=mm&r=g","contentUrl":"https:\/\/secure.gravatar.com\/avatar\/e9c468b7c98137ecdd5508befa660c205a7978133257080a37fb0b1362d53411?s=96&d=mm&r=g","caption":"N-able"}}]}},"_links":{"self":[{"href":"https:\/\/www.n-able.com\/de\/wp-json\/wp\/v2\/posts\/6519","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.n-able.com\/de\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.n-able.com\/de\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.n-able.com\/de\/wp-json\/wp\/v2\/users\/24"}],"replies":[{"embeddable":true,"href":"https:\/\/www.n-able.com\/de\/wp-json\/wp\/v2\/comments?post=6519"}],"version-history":[{"count":0,"href":"https:\/\/www.n-able.com\/de\/wp-json\/wp\/v2\/posts\/6519\/revisions"}],"wp:attachment":[{"href":"https:\/\/www.n-able.com\/de\/wp-json\/wp\/v2\/media?parent=6519"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}