ป้องกันการโจมตีแบบ DoS บน FreeBSD |

2005/Aug/20

ป้องกันการโจมตีแบบ DoS บน FreeBSD

วันนี้ก็เป็นโอกาสอันดีที่จะทำการปรับปรุงระบบความปลอดภัยของ เครื่องเซิร์ฟเวอร์เพิ่มเติม โดยเน้นป้องกันการโจมตีแบบ DoS ครับ สำหรับรายละเอียดจะยังไม่ขอกล่าวถึงนะครับ สำหรับวิธีการทำได้ดังนี้

1. แก้ไขไฟล์ /etc/sysctl.conf โดยเพิ่มข้อมูลเข้าไปดังนี้

net.inet.tcp.msl=7500
net.inet.tcp.blackhole=2
net.inet.udp.blackhole=1
net.inet.icmp.icmplim=50
kern.ipc.somaxconn=32768

2. ทำ DEVICE_POLLING ให้กับเน็ตเวิร์คการ์ด โดยการคอมไพล์เคอร์เนลครับ โดยอุปกรณ์ที่สามารถทำ DEVICE_POLLING ได้ มีดังนี้

dc
em
fxp
nge
rl
sis

ซึ่งวิธีการทำก็คือ เพิ่ม options DEVICE_POLLING เข้าไปในเคอร์เนล แล้วก็คอมไพล์ใหม่ครับ ต่อมาก็เพิ่มข้อมูลเข้าไปในไฟล์ /etc/sysctl.conf

kern.polling.enable=1

จากนั้นก็รีบูตระบบใหม่ครับ
สำหรับรายละเอียดของแต่ละออฟชันที่เพิ่มเข้าไปนั้น สามารถอ่านได้จากแหล่งช้อมูลอ้างอิงนะครับ

แหล่งข้อมูล :
http://www.onlamp.com/pub/a/bsd/2004/06/24/anti_dos.html
http://silverwraith.com/papers/freebsd-tuning.php

posted by chatpong, at 2005-Aug-20 04:24:52821

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