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Chapter 10 Security

Chapter 10 Security. A typical secured network. Recognizing Security Threats. 1- Application-layer attacks Ex: http://www. companyname.com/scripts/..%5c../winnt/system32/cmd.exe?/c+dir+c: 2- Autorooters 3- Backdoors

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Chapter 10 Security

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  1. Chapter 10Security

  2. A typical secured network

  3. Recognizing Security Threats • 1- Application-layer attacks • Ex: • http://www. companyname.com/scripts/..%5c../winnt/system32/cmd.exe?/c+dir+c:\ • 2- Autorooters • 3- Backdoors • 4- Denial of service (DoS) and distributed denial of service (DDoS) attacks • TCP SYN flood (SYN,SYN-ACK, & ACK) • Ping of death • Tribe Flood Network (TFN) and Tribe Flood Network 2000 (TFN2K) • Stacheldraht • 5- IP spoofing • 6- Man-in-the-middle attacks (Using Sniffer) • 7- Network reconnaissance (port scans, DNS queries, • and ping sweeps) • 8- Packet sniffers • 9- Password attacks (IP spoofing, packet sniffing, & Trojan horses) • 10- Brute force attack • 11- Port redirection attacks • 12- Trojan horse attacks and viruses • 13- Trust exploitation attacks

  4. Mitigating Security Threats • 1- Cisco’s IOS Firewall • Stateful IOS Firewall inspection engine using Context-Based Access Control (CBAC) • Intrusion detection • Firewall voice traversal • ICMP inspection • Authentication proxy (RADIUS or TACACS+) • Router(config)#enable use-tacacs • Router(config)#tacacs-server ? • host Specify a TACACS server • key Set TACACS+ encryption key • timeout Time to wait for a TACACS server to reply • Router(config)#enable last-resort • Destination URL policy management • Per-user firewalls • Cisco IOS router and firewall provisioning • Denial of service (DoS) detection and prevention • Dynamic port mapping • Java applet blocking • 2- Basic and Advanced Traffic Filtering • Policy-based, multi-interface support • Network Address Translation (NAT) • Time-based access lists • Peer router authentication (RIPv2, EIGRP, or OSPF)

  5. Access Lists • 1- Standard access lists • 2- Extended access lists • 3- Advanced access lists • a- Inbound access lists • b- Outbound access lists • Uses of Access lists • Traffic filtration • Telnet filtration • General Tips • Deny any addresses from your internal networks. • Deny any local host addresses (127.0.0.0/8). • Deny any reserved private addresses. • Deny any addresses in the IP multicast address range (224.0.0.0/4).

  6. Standard Access Lists Router(config)#access-list NO. Action Source Router(config)#access-list ? <1-99> IP standard access list <100-199> IP extended access list <1100-1199> Extended 48-bit MAC address access list <1300-1999> IP standard access list (expanded range) <200-299> Protocol type-code access list <2000-2699> IP extended access list (expanded range) <700-799> 48-bit MAC address access list compiled Enable IP access-list compilation dynamic-extended Extend the dynamic ACL absolute timer rate-limit Simple rate-limit specific access list Router(config)#access-list 10 ? deny Specify packets to reject permit Specify packets to forward remark Access list entry comment Router(config)#access-list 10 deny ? Hostname or A.B.C.D Address to match any Any source host host A single host address Router(config-if)#ip access-group 10 out (or in)

  7. Wildcard Masking Router(config)#access-list 10 deny 172.16.10.0 0.0.0.255 Router(config)#access-list 10 deny 172.16.0.0 0.0.255.255 Router(config)#access-list 10 deny 172.16.16.0 0.0.3.255 Controlling VTY (Telnet) Access Router(config)#access-list 50 permit 172.16.10.3 Router(config)#line vty 0 4 Router(config-line)#access-class 50 in

  8. Extended Access Lists Router(config)#access-list NO. Action Protocol Source Destination Condition Port no. Ex: Router(config)#access-list 110 permit tcp any host 172.16.30.2 eq 80 Router(config)#access-list 110 deny tcp any host 172.16.30.2 gt 1023 Router(config)#int s0 Router(config-if)#ip access-group 110 out

  9. Access Lists Example

  10. Advanced Access Lists 1- Named ACLs 2- Switch Port ACLs 3- Time based ACLs 1- Named ACLs Router(config)#ip access-list ? extended Extended Acc logging Control access list logging standard Standard Access List Router(config)#ip access-list standard BlockSales Router(config-std-nacl)#deny 172.16.40.0 0.0.0.255 Router(config-std-nacl)#permit any Router(config-std-nacl)#exit

  11. 2- Switch Port ACLs Conditions 1- Inbound only. 2- Named only. Switch(config)#mac access-list extended Name of list Switch(config-ext-macl)#Action Source Destination Ex: Switch(config)#mac access-list extended Block_MAC_Sales Switch(config-extended-macl)#deny any host 000d.29bd.4b85 Switch(config-extended-macl)#permit any any Switch(config-ext-macl)#int f0/6 Switch(config-if)#mac access-group Block_MAC_Sales in

  12. 3- Time-Based ACLs Router(config)#time-range no-http Router(config-time-range)#periodic we? Wednesday weekdays weekend Router(config-time-range)#periodic weekend ? hh:mm Starting time Router(config-time-range)#periodic weekend 06:00 to 12:00 Router(config-time-range)#exit Router(config)#time-range tcp-yes Router(config-time-range)#periodic weekend 06:00 to 12:00 Router(config-time-range)#exit Router(config)#ip access-list extended Time Router(config-ext-nacl)#deny tcp any any eq www time-range no-http Router(config-ext-nacl)#permit tcp any any time-range tcp-yes Router(config-ext-nacl)#interface f0/0 Router(config-if)#ip access-group Time in

  13. Remarking Access Lists Router#config t Router(config)#access-list 110 remark Permit Bob from Sales Only To Finance Router(config)#access-list 110 permit ip host 172.16.10.1 172.16.20.0 0.0.0.255 Router(config)#access-list 110 deny ip 172.16.10.0 0.0.0.255 172.16.20.0 0.0.0.255

  14. Using SSH instead of Telnet 1- Enable the HTTP/HTTPS server Router(config)#ip http server Router(config)#ip http secure-server % Generating 1024 bit RSA keys, keys will be non-exportable...[OK] Router(config)#ip http authentication local 2- Create a user account using privilege level 15 (the highest level) Router(config)#username cisco privilege ? <0-15> User privilege level Router(config)#username cisco privilege 15 password ? 0 Specifies an UNENCRYPTED password will follow 7 Specifies a HIDDEN password will follow LINE The UNENCRYPTED (cleartext) user password Router(config)#username cisco privilege 15 password 0 cisco

  15. 3- Configure the console, SSH, and Telnet to provide local login authentication at privilege level access Router(config)#line console 0 Router(config-line)#login local Router(config-line)#exit Router(config)#line vty 0 ? <1-1180> Last Line number <cr> Router(config)#line vty 0 1180 Router(config-line)#privilege level 15 Router(config-line)#login local Router(config-line)#transport input telnet Router(config-line)#transport input telnet ssh Router(config-line)#^Z Router#clock set 00:00:00 21 mar 2009

  16. Viewing Access Lists Router#show access-list Router#show access-list 110 Router#show ip access-list Router#show ip interface Router#show running-config Switch#Show mac access-group

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