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SecPath防火墙分片报文攻击防范典型配置

2006-09-25 发表

SecPath防火墙分片报文攻击防范典型配置

 

一、组网需求

部署SecPath防火墙,对IP分片报文攻击进行防范,以保护FTP Server 11.0.0.1/24。

二、组网图

    软件版本如下:

    SecPath10FVRP 3.40 ESS 1604

三、配置步骤

[DOWN] dis cur                                                                 

#                                                                               

 sysname DOWN                                                                  

#                                                                              

 firewall packet-filter enable                                                  

 firewall packet-filter default permit                                         

#                                                                              

 undo connection-limit enable                                                   

 connection-limit default deny                                                 

 connection-limit default amount upper-limit 50 lower-limit 20                 

#                                                                               

 firewall statistic system enable                                              

#                                                                              

radius scheme system                                                           

#                                                                              

domain system                                                                  

#                                                                              

local-user admin                                                               

 password cipher .]@USE=B,53Q=^Q`MAF4<1!!                                      

 service-type telnet terminal                                                  

 level 3                                                                        

 service-type ftp                                                              

#                                                                              

acl number 3000                                                                 

//阻止到达server的IP分片报文                   

 rule 1 deny ip destination 11.0.0.1 0 fragment  

//允许ftp分片报文通过   

 rule 2 permit tcp destination 11.0.0.1 0 destination-port eq ftp fragment     

#                                                                               

interface Ethernet1/0                                                          

 ip address 10.0.0.254 255.255.0.0                                             

 firewall packet-filter 3000 inbound            //在接口上应用acl                       

#                                                                              

interface Ethernet2/0                                                          

 speed 10                                                                      

 duplex full                                                                   

 ip address 11.0.0.254 255.255.255.0                                           

#                                                                              

interface NULL0                                                                 

#                                                                              

firewall zone local                                                            

 set priority 100                                                               

#                                                                              

firewall zone trust                                                            

 add interface Ethernet2/0                                                      

 set priority 85                                                               

#                                                                              

firewall zone untrust                                                           

 add interface Ethernet1/0                                                     

 set priority 5                                                                

#                                                                               

firewall zone DMZ                                                              

 set priority 50                                                               

#                                                                              

firewall interzone local trust                                                 

#                                                                              

firewall interzone local untrust                                               

#                                                                               

firewall interzone local DMZ                                                   

#                                                                              

firewall interzone trust untrust                                                

#                                                                              

firewall interzone trust DMZ                                                   

#                                                                               

firewall interzone DMZ untrust                                                 

#                                                                              

 FTP server enable                                                              

#                                                                              

user-interface con 0                                                           

user-interface vty 0 4                                                          

 authentication-mode scheme                                                    

#                                                                              

return

                                   

                                                                         

四、配置关键点

1.ACL中配置对分片报文的阻断;

2.在接口上应用ACL

五、验证结果

在攻击机Attacker10.0.0.1上对11.0.0.1进行ping大包,PC会对ping报文进行分片,结果无法ping11.0.0.1

在攻击机上ftp 11.0.0.1,正常。

[DOWN]dis acl 3000                                                             

Advanced ACL  3000, 2 rules                                                     

Acl's step is 1                                                                

 rule 1 deny ip destination 11.0.0.1 0 fragment (0 times matched)              

 rule 2 permit tcp destination 11.0.0.1 0 destination-port eq ftp fragment (0 ti

mes matched)                                                                   

                                                                               

[DOWN]dis acl 3000                                                             

Advanced ACL  3000, 2 rules                                                    

Acl's step is 1                                                                

 rule 1 deny ip destination 11.0.0.1 0 fragment (108 times matched)            

 rule 2 permit tcp destination 11.0.0.1 0 destination-port eq ftp fragment (0 ti

mes matched)