{"id":154,"date":"2011-11-24T20:07:00","date_gmt":"2011-11-24T20:07:00","guid":{"rendered":"http:\/\/pheonixsolutions.com\/?p=154"},"modified":"2026-05-08T07:23:06","modified_gmt":"2026-05-08T01:53:06","slug":"steps-to-check-the-opened-ports-in-ip-tables","status":"publish","type":"post","link":"https:\/\/pheonixsolutions.com\/blog\/steps-to-check-the-opened-ports-in-ip-tables\/","title":{"rendered":"Steps to check the opened ports in IP tables"},"content":{"rendered":"\n<h2 class=\"wp-block-heading\">Introduction<\/h2>\n\n\n\n<p>IPTables is a user-space utility in Linux used to configure and manage the Netfilter firewall framework. It helps administrators control incoming and outgoing network traffic based on defined security rules. Checking opened ports in IPTables is an essential task for system administrators to verify firewall configurations, troubleshoot connectivity issues, and ensure that only required services are accessible from external networks.<\/p>\n\n\n\n<p>This guide explains how to check opened ports configured through IPTables on a Linux server<\/p>\n\n\n\n<h2 class=\"wp-block-heading\">Prerequisites<\/h2>\n\n\n\n<p>Before proceeding, ensure the following requirements are met:<\/p>\n\n\n\n<ul class=\"wp-block-list\">\n<li>A Linux server with IPTables installed and configured<\/li>\n\n\n\n<li>Root or sudo access to the server<\/li>\n\n\n\n<li>Basic knowledge of Linux command-line operations<\/li>\n\n\n\n<li>SSH access to the server terminal<\/li>\n<\/ul>\n\n\n\n<p>You can verify whether IPTables is installed by running:<\/p>\n\n\n\n<pre class=\"wp-block-code\"><code>iptables --version<\/code><\/pre>\n\n\n\n<h2 class=\"wp-block-heading\">IMPLEMENTATION<\/h2>\n\n\n<div dir=\"ltr\" style=\"text-align: left;\"><span style=\"font-weight: bold;\">To view the ports that are already opened in the server, execute the following command.<\/span>\n<p>netstat -plan |grep LISTEN<\/p>\n<p><span style=\"font-weight: bold;\">Steps to open a new port in IP tables<\/span><\/p>\n<p>Before opening a port, you should be aware of why are you opening the port and what is the port being used for.<\/p>\n<p><span style=\"font-weight: bold;\">Save the existing IP tables.<\/span><\/p>\n<p>root@server [~]# \/etc\/init.d\/iptables save<br \/>Saving firewall rules to \/etc\/sysconfig\/iptables: [ OK ]<\/p>\n<p><span style=\"font-weight: bold;\">To open a port, execute the commands below.<\/span><\/p>\n<p>iptables -A allowed -p tcp &#8211;dport portno -s IPaddress -j ACCEPT<br \/>iptables -A allowed -p udp &#8211;dport portno -s IPaddress -j ACCEPT<\/p>\n<p><span style=\"font-weight: bold;\">To allow all IP address,<\/span><\/p>\n<p>iptables -A INPUT -i eth0 -p tcp -m tcp &#8211;dport portno -j ACCEPT<\/p>\n<p><span style=\"font-weight: bold;\">Check whether the Port is allowed.<\/span><\/p>\n<p>root@server [~]# iptables -nL | grep :3306<br \/>ACCEPT tcp &#8212; 0.0.0.0\/0 0.0.0.0\/0 tcp dpt:3306<br \/>ACCEPT tcp &#8212; 0.0.0.0\/0 0.0.0.0\/0 tcp dpt:3306<\/p>\n<\/div>\n<p>\u00a0<\/p>\n<h2>CONCLUSION<\/h2>\n<p>Checking opened ports in IPTables is an important step in maintaining Linux server security and troubleshooting network access issues. By reviewing INPUT chain rules, filtering ACCEPT entries, and verifying active listening services, administrators can ensure that only necessary ports are exposed to external traffic. Regular firewall audits help reduce security risks and maintain proper server access control.<\/p>","protected":false},"excerpt":{"rendered":"<p>Introduction IPTables is a user-space utility in Linux used to configure and manage the Netfilter firewall framework. It helps administrators control incoming and outgoing network traffic based on defined security rules. Checking opened ports in IPTables is an essential task for system administrators to verify firewall configurations, troubleshoot connectivity issues,&hellip; <a href=\"https:\/\/pheonixsolutions.com\/blog\/steps-to-check-the-opened-ports-in-ip-tables\/\" class=\"more-link read-more\" rel=\"bookmark\">Continue Reading <span class=\"screen-reader-text\">Steps to check the opened ports in IP tables<\/span><i class=\"fa fa-arrow-right\"><\/i><\/a><\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"_jetpack_newsletter_access":"","_jetpack_dont_email_post_to_subs":false,"_jetpack_newsletter_tier_id":0,"_jetpack_memberships_contains_paywalled_content":false,"_jetpack_memberships_contains_paid_content":false,"footnotes":"","jetpack_post_was_ever_published":false},"categories":[1],"tags":[],"class_list":{"0":"post-154","1":"post","2":"type-post","3":"status-publish","4":"format-standard","5":"hentry","6":"category-uncategorized","7":"h-entry","9":"h-as-article"},"yoast_head":"<!-- This site is optimized with the Yoast SEO plugin v27.6 - https:\/\/yoast.com\/product\/yoast-seo-wordpress\/ -->\n<title>Pheonix Solutions - We Empower Your Business Growth<\/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:\/\/pheonixsolutions.com\/blog\/steps-to-check-the-opened-ports-in-ip-tables\/\" \/>\n<meta property=\"og:locale\" content=\"en_US\" \/>\n<meta property=\"og:type\" content=\"article\" \/>\n<meta property=\"og:title\" content=\"Pheonix Solutions - We Empower Your Business Growth\" \/>\n<meta property=\"og:description\" content=\"Introduction IPTables is a user-space utility in Linux used to configure and manage the Netfilter firewall framework. 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