Packet Filtering Firewall \u2014 With Real Examples<\/h1>\n\n
A Packet Filtering Firewall<\/strong> is the most basic type of network firewall. It examines source IP, destination IP, port numbers, and protocol before allowing or blocking traffic. This is called Layer-3\/Layer-4 filtering<\/strong> in the OSI model.<\/p>\n\n

How Packet Filtering Works<\/h2>\n
Packet filtering checks incoming and outgoing packets using rules:<\/p>\n
\nIF Source IP = Allowed AND Port = 80\nTHEN Permit traffic\nELSE Block\n<\/pre>\n\n
Key Fields Checked<\/h2>\n
\n
Source IP<\/li>\n
Destination IP<\/li>\n
Source Port<\/li>\n
Destination Port<\/li>\n
Protocol (TCP\/UDP\/ICMP)<\/li>\n<\/ul>\n\n
Real-Life Example<\/h2>\n
\nPermit 192.168.1.5 \u2192 Port 443 (HTTPS)\nDeny 10.5.20.50 \u2192 Port 22 (SSH)\n<\/pre>\n\n
Advantages<\/h2>\n
\n
Fast performance<\/li>\n
Low resource usage<\/li>\n
Easy to configure<\/li>\n
Good for small networks\/home users<\/li>\n<\/ul>\n\n
Limitations<\/h2>\n
\n
Cannot inspect packet contents<\/li>\n
No protection against encrypted threats<\/li>\n
Does not detect malware\/trojans<\/li>\n
Cannot identify applications<\/li>\n<\/ul>\n\n
Where Packet Filters Are Used<\/h2>\n
\n
Home routers<\/li>\n
Basic firewalls<\/li>\n
Cloud security groups (AWS\/GCP\/Azure)<\/li>\n
ISP perimeter filters<\/li>\n<\/ul>\n\n
Example AWS Security Group Rule<\/h2>\n
\nAllow: 0.0.0.0\/0 \u2192 TCP 443\nDeny: All others\n<\/pre>\n\n
Conclusion<\/h2>\n
Packet filtering is essential for basic network security. While modern networks need deep inspection firewalls, packet filtering is still the foundation of network security rules.<\/p>\n<\/div>\n<\/body>","protected":false},"excerpt":{"rendered":"
Packet Filtering Firewall \u2014 With Real Examples A Packet Filtering Firewall is the most basic type of network firewall. It examines source IP, destination IP, port numbers, and protocol before allowing or blocking traffic. This is called Layer-3\/Layer-4 filtering in the OSI model. How Packet Filtering Works Packet filtering checks incoming and outgoing packets using […]<\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"om_disable_all_campaigns":false,"pagelayer_contact_templates":[],"_pagelayer_content":"","footnotes":""},"categories":[4],"tags":[],"class_list":["post-78","post","type-post","status-publish","format-standard","hentry","category-firewall"],"yoast_head":"\nPacket Filtering Firewall \u2014 With Real Examples - IPv4Chicken<\/title>\n<meta name=\"robots\" content=\"index, follow, max-snippet:-1, max-image-preview:large, max-video-preview:-1\" \/>\n<link rel=\"canonical\" href=\"https:\/\/ipv4chicken.com\/tech\/packet-filtering-firewall-with-real-examples\/\" \/>\n<meta property=\"og:locale\" content=\"en_US\" \/>\n<meta property=\"og:type\" content=\"article\" \/>\n<meta property=\"og:title\" content=\"Packet Filtering Firewall \u2014 With Real Examples - IPv4Chicken\" \/>\n<meta property=\"og:description\" content=\"Packet Filtering Firewall \u2014 With Real Examples A Packet Filtering Firewall is the most basic type of network firewall. It examines source IP, destination IP, port numbers, and protocol before allowing or blocking traffic. This is called Layer-3\/Layer-4 filtering in the OSI model. How Packet Filtering Works Packet filtering checks incoming and outgoing packets using […]\" \/>\n<meta property=\"og:url\" content=\"https:\/\/ipv4chicken.com\/tech\/packet-filtering-firewall-with-real-examples\/\" \/>\n<meta property=\"og:site_name\" content=\"IPv4Chicken\" \/>\n<meta property=\"article:published_time\" content=\"2025-11-05T19:09:22+00:00\" \/>\n<meta name=\"author\" content=\"admin\" \/>\n<meta name=\"twitter:card\" content=\"summary_large_image\" \/>\n<meta name=\"twitter:label1\" content=\"Written by\" \/>\n\t<meta name=\"twitter:data1\" content=\"admin\" \/>\n\t<meta name=\"twitter:label2\" content=\"Est. reading time\" \/>\n\t<meta name=\"twitter:data2\" content=\"1 minute\" \/>\n<script type=\"application\/ld+json\" class=\"yoast-schema-graph\">{\"@context\":\"https:\\\/\\\/schema.org\",\"@graph\":[{\"@type\":\"Article\",\"@id\":\"https:\\\/\\\/ipv4chicken.com\\\/tech\\\/packet-filtering-firewall-with-real-examples\\\/#article\",\"isPartOf\":{\"@id\":\"https:\\\/\\\/ipv4chicken.com\\\/tech\\\/packet-filtering-firewall-with-real-examples\\\/\"},\"author\":{\"name\":\"admin\",\"@id\":\"https:\\\/\\\/ipv4chicken.com\\\/tech\\\/#\\\/schema\\\/person\\\/1d835bee6b0fb8ea8238f34395837ddf\"},\"headline\":\"Packet Filtering Firewall \u2014 With Real Examples\",\"datePublished\":\"2025-11-05T19:09:22+00:00\",\"mainEntityOfPage\":{\"@id\":\"https:\\\/\\\/ipv4chicken.com\\\/tech\\\/packet-filtering-firewall-with-real-examples\\\/\"},\"wordCount\":161,\"commentCount\":0,\"articleSection\":[\"Firewall\"],\"inLanguage\":\"en-US\",\"potentialAction\":[{\"@type\":\"CommentAction\",\"name\":\"Comment\",\"target\":[\"https:\\\/\\\/ipv4chicken.com\\\/tech\\\/packet-filtering-firewall-with-real-examples\\\/#respond\"]}]},{\"@type\":\"WebPage\",\"@id\":\"https:\\\/\\\/ipv4chicken.com\\\/tech\\\/packet-filtering-firewall-with-real-examples\\\/\",\"url\":\"https:\\\/\\\/ipv4chicken.com\\\/tech\\\/packet-filtering-firewall-with-real-examples\\\/\",\"name\":\"Packet Filtering Firewall \u2014 With Real Examples - IPv4Chicken\",\"isPartOf\":{\"@id\":\"https:\\\/\\\/ipv4chicken.com\\\/tech\\\/#website\"},\"datePublished\":\"2025-11-05T19:09:22+00:00\",\"author\":{\"@id\":\"https:\\\/\\\/ipv4chicken.com\\\/tech\\\/#\\\/schema\\\/person\\\/1d835bee6b0fb8ea8238f34395837ddf\"},\"breadcrumb\":{\"@id\":\"https:\\\/\\\/ipv4chicken.com\\\/tech\\\/packet-filtering-firewall-with-real-examples\\\/#breadcrumb\"},\"inLanguage\":\"en-US\",\"potentialAction\":[{\"@type\":\"ReadAction\",\"target\":[\"https:\\\/\\\/ipv4chicken.com\\\/tech\\\/packet-filtering-firewall-with-real-examples\\\/\"]}]},{\"@type\":\"BreadcrumbList\",\"@id\":\"https:\\\/\\\/ipv4chicken.com\\\/tech\\\/packet-filtering-firewall-with-real-examples\\\/#breadcrumb\",\"itemListElement\":[{\"@type\":\"ListItem\",\"position\":1,\"name\":\"Home\",\"item\":\"https:\\\/\\\/ipv4chicken.com\\\/tech\\\/\"},{\"@type\":\"ListItem\",\"position\":2,\"name\":\"Packet Filtering Firewall \u2014 With Real Examples\"}]},{\"@type\":\"WebSite\",\"@id\":\"https:\\\/\\\/ipv4chicken.com\\\/tech\\\/#website\",\"url\":\"https:\\\/\\\/ipv4chicken.com\\\/tech\\\/\",\"name\":\"IPv4Chicken\",\"description\":\"Technical SOP\",\"potentialAction\":[{\"@type\":\"SearchAction\",\"target\":{\"@type\":\"EntryPoint\",\"urlTemplate\":\"https:\\\/\\\/ipv4chicken.com\\\/tech\\\/?s={search_term_string}\"},\"query-input\":{\"@type\":\"PropertyValueSpecification\",\"valueRequired\":true,\"valueName\":\"search_term_string\"}}],\"inLanguage\":\"en-US\"},{\"@type\":\"Person\",\"@id\":\"https:\\\/\\\/ipv4chicken.com\\\/tech\\\/#\\\/schema\\\/person\\\/1d835bee6b0fb8ea8238f34395837ddf\",\"name\":\"admin\",\"image\":{\"@type\":\"ImageObject\",\"inLanguage\":\"en-US\",\"@id\":\"https:\\\/\\\/secure.gravatar.com\\\/avatar\\\/4ff63f3440b165262c0e90314cb9071362406be85a27a08760ee3141345e6974?s=96&d=mm&r=g\",\"url\":\"https:\\\/\\\/secure.gravatar.com\\\/avatar\\\/4ff63f3440b165262c0e90314cb9071362406be85a27a08760ee3141345e6974?s=96&d=mm&r=g\",\"contentUrl\":\"https:\\\/\\\/secure.gravatar.com\\\/avatar\\\/4ff63f3440b165262c0e90314cb9071362406be85a27a08760ee3141345e6974?s=96&d=mm&r=g\",\"caption\":\"admin\"},\"sameAs\":[\"https:\\\/\\\/ipv4chicken.com\\\/tech\"],\"url\":\"https:\\\/\\\/ipv4chicken.com\\\/tech\\\/author\\\/admin\\\/\"}]}<\/script>\n","yoast_head_json":{"title":"Packet Filtering Firewall \u2014 With Real Examples - IPv4Chicken","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:\/\/ipv4chicken.com\/tech\/packet-filtering-firewall-with-real-examples\/","og_locale":"en_US","og_type":"article","og_title":"Packet Filtering Firewall \u2014 With Real Examples - IPv4Chicken","og_description":"Packet Filtering Firewall \u2014 With Real Examples A Packet Filtering Firewall is the most basic type of network firewall. It examines source IP, destination IP, port numbers, and protocol before allowing or blocking traffic. This is called Layer-3\/Layer-4 filtering in the OSI model. How Packet Filtering Works Packet filtering checks incoming and outgoing packets using […]","og_url":"https:\/\/ipv4chicken.com\/tech\/packet-filtering-firewall-with-real-examples\/","og_site_name":"IPv4Chicken","article_published_time":"2025-11-05T19:09:22+00:00","author":"admin","twitter_card":"summary_large_image","twitter_misc":{"Written by":"admin","Est. reading time":"1 minute"},"schema":{"@context":"https:\/\/schema.org","@graph":[{"@type":"Article","@id":"https:\/\/ipv4chicken.com\/tech\/packet-filtering-firewall-with-real-examples\/#article","isPartOf":{"@id":"https:\/\/ipv4chicken.com\/tech\/packet-filtering-firewall-with-real-examples\/"},"author":{"name":"admin","@id":"https:\/\/ipv4chicken.com\/tech\/#\/schema\/person\/1d835bee6b0fb8ea8238f34395837ddf"},"headline":"Packet Filtering Firewall \u2014 With Real Examples","datePublished":"2025-11-05T19:09:22+00:00","mainEntityOfPage":{"@id":"https:\/\/ipv4chicken.com\/tech\/packet-filtering-firewall-with-real-examples\/"},"wordCount":161,"commentCount":0,"articleSection":["Firewall"],"inLanguage":"en-US","potentialAction":[{"@type":"CommentAction","name":"Comment","target":["https:\/\/ipv4chicken.com\/tech\/packet-filtering-firewall-with-real-examples\/#respond"]}]},{"@type":"WebPage","@id":"https:\/\/ipv4chicken.com\/tech\/packet-filtering-firewall-with-real-examples\/","url":"https:\/\/ipv4chicken.com\/tech\/packet-filtering-firewall-with-real-examples\/","name":"Packet Filtering Firewall \u2014 With Real Examples - IPv4Chicken","isPartOf":{"@id":"https:\/\/ipv4chicken.com\/tech\/#website"},"datePublished":"2025-11-05T19:09:22+00:00","author":{"@id":"https:\/\/ipv4chicken.com\/tech\/#\/schema\/person\/1d835bee6b0fb8ea8238f34395837ddf"},"breadcrumb":{"@id":"https:\/\/ipv4chicken.com\/tech\/packet-filtering-firewall-with-real-examples\/#breadcrumb"},"inLanguage":"en-US","potentialAction":[{"@type":"ReadAction","target":["https:\/\/ipv4chicken.com\/tech\/packet-filtering-firewall-with-real-examples\/"]}]},{"@type":"BreadcrumbList","@id":"https:\/\/ipv4chicken.com\/tech\/packet-filtering-firewall-with-real-examples\/#breadcrumb","itemListElement":[{"@type":"ListItem","position":1,"name":"Home","item":"https:\/\/ipv4chicken.com\/tech\/"},{"@type":"ListItem","position":2,"name":"Packet Filtering Firewall \u2014 With Real Examples"}]},{"@type":"WebSite","@id":"https:\/\/ipv4chicken.com\/tech\/#website","url":"https:\/\/ipv4chicken.com\/tech\/","name":"IPv4Chicken","description":"Technical SOP","potentialAction":[{"@type":"SearchAction","target":{"@type":"EntryPoint","urlTemplate":"https:\/\/ipv4chicken.com\/tech\/?s={search_term_string}"},"query-input":{"@type":"PropertyValueSpecification","valueRequired":true,"valueName":"search_term_string"}}],"inLanguage":"en-US"},{"@type":"Person","@id":"https:\/\/ipv4chicken.com\/tech\/#\/schema\/person\/1d835bee6b0fb8ea8238f34395837ddf","name":"admin","image":{"@type":"ImageObject","inLanguage":"en-US","@id":"https:\/\/secure.gravatar.com\/avatar\/4ff63f3440b165262c0e90314cb9071362406be85a27a08760ee3141345e6974?s=96&d=mm&r=g","url":"https:\/\/secure.gravatar.com\/avatar\/4ff63f3440b165262c0e90314cb9071362406be85a27a08760ee3141345e6974?s=96&d=mm&r=g","contentUrl":"https:\/\/secure.gravatar.com\/avatar\/4ff63f3440b165262c0e90314cb9071362406be85a27a08760ee3141345e6974?s=96&d=mm&r=g","caption":"admin"},"sameAs":["https:\/\/ipv4chicken.com\/tech"],"url":"https:\/\/ipv4chicken.com\/tech\/author\/admin\/"}]}},"jetpack_featured_media_url":"","_links":{"self":[{"href":"https:\/\/ipv4chicken.com\/tech\/wp-json\/wp\/v2\/posts\/78","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/ipv4chicken.com\/tech\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/ipv4chicken.com\/tech\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/ipv4chicken.com\/tech\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/ipv4chicken.com\/tech\/wp-json\/wp\/v2\/comments?post=78"}],"version-history":[{"count":0,"href":"https:\/\/ipv4chicken.com\/tech\/wp-json\/wp\/v2\/posts\/78\/revisions"}],"wp:attachment":[{"href":"https:\/\/ipv4chicken.com\/tech\/wp-json\/wp\/v2\/media?parent=78"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/ipv4chicken.com\/tech\/wp-json\/wp\/v2\/categories?post=78"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/ipv4chicken.com\/tech\/wp-json\/wp\/v2\/tags?post=78"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}