Which of the following features is essential in a firewall if it is to support RTP sessions?()A. Remote consoleB. StatefulnessC. Address translationD. Zones

[问题1]A，隧道模式[问题2]（3）system-view （4）GigabitEthernet 1/0/2（5） 192.168.1.1 24或者192.168.1.1 255.255.255.0 （6） GigabitEthernet 1/0/2(7) firewall zone untrust (8) security-policy(9) trust (10) 192.168.100.0 24(11) permit (12) acl 3000(13) ip source 192.168.100.0 0.0.0.255 destination 192.168.200.0 0.0.0.255 （14）tunnel （15）ike proposal 10 [问题3]（17）AH （18）ESP
【解析】
[问题1]IPSec VPN应用场景分为站点到站点、端到端、端到站点三种模式。1）站点到站点（Site-to-Site）。站点到站点又称为网关到网关，多个异地机构利用运营商网络建立IPSec隧道，将各自的内部网络联系起来。2）端到端（End-to-End）。端到端又称为PC到PC，即两个PC之间的通信由IPSec完成。3）端到站点（End-to-Site）。端到站点，两个PC之间的通信由网关和异地PC之间的IPSec会话完成。

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[问题2] system-view[FIREWALL1] interface GigabitEthernet 1/0/2[FIREWALL1-GigabitEthernet1/0/2] ip address 192.168.1.1 24 [FIREWALL1-GigabitEthernet1/0/2] quit[FIREWALL1] interface GigabitEthernet 1/0/1[FIREWALL1-GigabitEthernet1/0/1] ip address 202.1.3.1 24[FIREWALL1-GigabitEthernet1/0/1] quit# 配置接口加入相应的安全区域。[FIREWALL1] firewall zone trust [FIREWALL1-zone-trust] add interface GigabitEthernet 1/0/2[FIREWALL1-zone-trust] quit[FIREWALL1] firewall zone untrust [FIREWALL1-zone-untrust] add interface GigabitEthernet 1/0/1[FIREWALL1-zone-untrust] quit2. 配置安全策略，允许私网指定网段进行报文交互。# 配置Trust域与Untrust域的安全策略，允许封装前和解封后的报文能通过[FIREWALL1] security-policy [FIREWALL1-policy-security] rule name 1[FIREWALL1-policy-security-rule-1] source-zone trust [FIREWALL1-policy-security-rule-1] destination-zone untrust[FIREWALL1-policy-security-rule-1] source-address 192.168.100.0 24 [FIREWALL1-policy-security-rule-1] destination-address 192.168.200.0 24[FIREWALL1-policy-security-rule-1] action permit [FIREWALL1-policy-security-rule-1] quit…..# 配置Local域与Untrust域的安全策略，允许IKE协商报文能正常通过FIREWALL1。[FIREWALL1-policy-security] rule name 3[FIREWALL1-policy-security-rule-3] source-zone local[FIREWALL1-policy-security-rule-3] destination-zone untrust[FIREWALL1-policy-security-rule-3] source-address 202.1.3.1 32[FIREWALL1-policy-security-rule-3] destination-address 202.1.5.1 32[FIREWALL1-policy-security-rule-3] action permit[FIREWALL1-policy-security-rule-3] quit…3. 配置IPSec隧道。# 配置访问控制列表，定义需要保护的数据流。[FIREWALL1] acl 3000[FIREWALL1-acl-adv-3000] rule permit ip source 192.168.100.0 0.0.0.255 destination 192.168.200.0 0.0.0.255 [FIREWALL1-acl-adv-3000] quit# 配置名称为tran1的IPSec安全提议。[FIREWALL1] ipsec proposal tran1[FIREWALL1-ipsec-proposal-tran1] encapsulation-mode tunnel [FIREWALL1-ipsec-proposal-tran1] transform esp[FIREWALL1-ipsec-proposal-tran1] esp authentication-algorithm sha2-256[FIREWALL1-ipsec-proposal-tran1] esp encryption-algorithm aes[FIREWALL1-ipsec-proposal-tran1] quit# 配置序号为10的IKE安全提议。[FIREWALL1] ike proposal 10 [FIREWALL1-ike-proposal-10] authentication-method pre-share[FIREWALL1-ike-proposal-10] authentication-algorithm sha2-256[FIREWALL1-ike-proposal-10] quit# 配置IKE用户信息表。[FIREWALL1] ike user-table 1[FIREWALL1-ike-user-table-1] user id-type ip 202.1.5.1 pre-shared-key Admin@gkys[FIREWALL1-ike-user-table-1] quit# 配置IKE Peer。[FIREWALL1] ike peer b[FIREWALL1-ike-peer-b] ike-proposal 10[FIREWALL1-ike-peer-b] user-table 1[FIREWALL1-ike-peer-b] quit# 配置名称为map_temp序号为1的IPSec安全策略模板。[FIREWALL1] ipsec policy-template map_temp 1[FIREWALL1-ipsec-policy-template-map_temp-1] security acl 3000[FIREWALL1-ipsec-policy-template-map_temp-1] proposal tran1[FIREWALL1-ipsec-policy-template-map_temp-1] ike-peer b[FIREWALL1-ipsec-policy-template-map_temp-1] reverse-route enable[FIREWALL1-ipsec-policy-template-map_temp-1] quit# 在IPSec安全策略map1中引用安全策略模板map_temp。[FIREWALL1] ipsec policy map1 10 isakmp template map_temp# 在接口GigabitEthernet 1/0/1上应用安全策略map1。[FIREWALL1] interface GigabitEthernet 1/0/1[FIREWALL1-GigabitEthernet1/0/1] ipsec policy map1[FIREWALL1-GigabitEthernet1/0/1] quit[问题3]（1）AH。认证头（Authentication Header，AH）是IPSec体系结构中的一种主要协议，它为IP数据报提供完整性检查与数据源认证，并防止重放攻击。AH不支持数据加密。AH常用摘要算法（单向Hash函数）MD5和SHA1实现摘要和认证，确保数据完整。（2）ESP。封装安全载荷（Encapsulating Security Payload，ESP）可以同时提供数据完整性确认和数据加密等服务。ESP通常使用DES、3DES、AES等加密算法实现数据加密，使用MD5或SHA-1来实现摘要和认证，确保数据完整。