2. DOS/DDOS
CP/M
MS-DOS
MS” Microsoft
◦PC-DOS
PC” Per
◦Novell’s DOS
DR-DOS Digital Research

3. Distributed Denial of Service (DDoS)
DDoS
ICT
DDoS

4. DDoS
SYN flood, UDP flood, ICMP flood, Smurf, Fraggle

5. SYN Flood
source IP
address TCP
SYN
TCP source address
SYN-ACK
source IP address half-open
SYN flood
SYN
flood

6. ICMP Flood
ICMP
UDP Flood
UDP
UDP packet port
(DNS)

7. Teardrop
Fragment
Fragment
Offset
Teardrop Offset
Land Attack
SYN
SYN ACK
IP Address IP Address
IP Address Hacker IP Address
IP Address
SYN ACK
SYN ACK
SYN ACK

8. 6. Smurf
ICMP Echo Request broadcast address
amplifier)
source IP address IP address
ICMP Echo Reply IP address
DoS
DoS

10. Network
LAN

12. SPAM Email Malicious Email
content
Attached File
SPAM Email
ANTI-
SPAM ACT"
SPAMMER SPAM e-
mail

14. SPAM Email Malicious
Email content
ANTI-
SPAM/ANTI-Virus Internet Gateway
DMZ SPAM e-mail
- e-mail ANTI-SPAM
Software PC Client
e-mail
HTML Character
Plain Text