{"id":93,"date":"2012-01-29T18:16:00","date_gmt":"2012-01-29T18:16:00","guid":{"rendered":"http:\/\/pheonixsolutions.com\/?p=93"},"modified":"2026-05-31T10:16:42","modified_gmt":"2026-05-31T04:46:42","slug":"few-steps-to-be-taken-when-you-feel-that-the-server-is-under-ddos-attack","status":"publish","type":"post","link":"https:\/\/pheonixsolutions.com\/blog\/few-steps-to-be-taken-when-you-feel-that-the-server-is-under-ddos-attack\/","title":{"rendered":"A few steps to be taken when you feel that the server is under DDOS attack:"},"content":{"rendered":"\n<h2 class=\"wp-block-heading\">Introduction<\/h2>\n\n\n\n<p class=\"wp-block-paragraph\">A DDOS (Distributed Denial of Service) attack can cause high server load, excessive resource usage, and service interruptions. When you suspect that a server is under a DDoS attack, it is important to identify the source of the traffic and take immediate action to minimize the impact on the server.<\/p>\n\n\n\n<hr class=\"wp-block-separator has-alpha-channel-opacity\"\/>\n\n\n\n<h2 class=\"wp-block-heading\">Prerequisites<\/h2>\n\n\n\n<ul class=\"wp-block-list\">\n<li>Root or SSH access to the server<\/li>\n\n\n\n<li>Basic knowledge of Linux networking commands<\/li>\n\n\n\n<li>APF or CSF firewall installed on the server<\/li>\n<\/ul>\n\n\n\n<hr class=\"wp-block-separator has-alpha-channel-opacity\"\/>\n\n\n\n<h2 class=\"wp-block-heading\">Implementation<\/h2>\n\n\n\n<h3 class=\"wp-block-heading\">Few Steps to Be Taken When You Feel That the Server Is Under a DDoS Attack<\/h3>\n\n\n\n<hr class=\"wp-block-separator has-alpha-channel-opacity\"\/>\n\n\n\n<h3 class=\"wp-block-heading\">Step 1<\/h3>\n\n\n\n<p class=\"wp-block-paragraph\">Check the server load using the following command:<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">w<\/p>\n\n\n\n<hr class=\"wp-block-separator has-alpha-channel-opacity\"\/>\n\n\n\n<h3 class=\"wp-block-heading\">Step 2<\/h3>\n\n\n\n<p class=\"wp-block-paragraph\">Check which service is utilizing the maximum CPU usage:<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">nice top<\/p>\n\n\n\n<hr class=\"wp-block-separator has-alpha-channel-opacity\"\/>\n\n\n\n<h3 class=\"wp-block-heading\">Step 3<\/h3>\n\n\n\n<p class=\"wp-block-paragraph\">Check which IP address is creating the maximum number of connections using the following command:<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">netstat -anpl | grep :80 | awk &#8216;{print $5}&#8217; | cut -d&#8221;:&#8221; -f1 | sort | uniq -c | sort -n<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">Note:<br>&#8220;print $5&#8221; indicates the external IP addresses connected to the server.<\/p>\n\n\n\n<hr class=\"wp-block-separator has-alpha-channel-opacity\"\/>\n\n\n\n<h3 class=\"wp-block-heading\">Step 4<\/h3>\n\n\n\n<p class=\"wp-block-paragraph\">Check the IP addresses configured on the server that are receiving the maximum connections using the following command:<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">netstat -alpn | grep :80 | awk &#8216;{print $4}&#8217; | cut -d: -f1 | sort | uniq -c<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">or<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">netstat -alpn | grep :80 | awk &#8216;{print $4}&#8217; | awk -F: &#8216;{print $(NF-1)}&#8217; | sort | uniq -c<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">Note:<br>&#8220;print $4&#8221; indicates the IP addresses configured on the server.<\/p>\n\n\n\n<hr class=\"wp-block-separator has-alpha-channel-opacity\"\/>\n\n\n\n<h3 class=\"wp-block-heading\">Step 5<\/h3>\n\n\n\n<p class=\"wp-block-paragraph\">Block the suspicious IP address using the firewall.<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">For APF firewall:<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">apf -d IPADDRESS<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">For CSF firewall:<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">csf -d IPADDRESS<\/p>\n\n\n\n<hr class=\"wp-block-separator has-alpha-channel-opacity\"\/>\n\n\n\n<h2 class=\"wp-block-heading\">Conclusion<\/h2>\n\n\n\n<p class=\"wp-block-paragraph\">By monitoring server load, identifying suspicious connections, and blocking abusive IP addresses using firewall tools such as APF or ConfigServer Security &amp; Firewall, you can reduce the impact of DDOS attacks and improve server stability.<\/p>\n","protected":false},"excerpt":{"rendered":"<p>Introduction A DDOS (Distributed Denial of Service) attack can cause high server load, excessive resource usage, and service interruptions. 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