本文档提供了使用 Network Time Protocol (NTP) 对 PIX/ASA 安全设备时钟与网络时间服务器进行同步的示例配置。ASA1 直接与网络时间服务器进行通信。ASA2 通过 IPsec 隧道向 ASA1 传送 NTP 流量,后者反过来将数据包转发给网络时间服务器。
有关在8.3及更高版本的Cisco ASA上进行相同配置的详细信息,请参阅ASA 8.3及更高版本:使用和不使用IPSec隧道的NTP配置示例。
注意:路由器还可以用作NTP服务器来同步PIX/ASA安全设备时钟。
尝试进行此配置之前,请确保满足以下要求:
必须建立端到端 IPsec 连接才能开始此 NTP 配置。
必须为数据加密标准 (DES) 加密(在最低加密级别)启用安全设备许可证。
本文档中的信息基于以下软件和硬件版本。
Cisco 自适应安全设备 (ASA) 版本 7.x 及更高版本
ASDM 版本 5.x 及更高版本
注意:要使ASDM可以配置ASA,请参阅允许ASDM进行HTTPS访问。
本文档中的信息都是基于特定实验室环境中的设备编写的。本文档中使用的所有设备最初均采用原始(默认)配置。如果您使用的是真实网络,请确保您已经了解所有命令的潜在影响。
此配置也可用于 Cisco PIX 500 系列安全设备,这些设备运行版本 7.x 及更高版本。
注意:PIX版本6.2中已添加NTP支持。要在Cisco PIX防火墙上配置NTP,请参阅PIX 6.2:有和没有IPSec隧道的NTP配置示例。
有关文档约定的更多信息,请参考 Cisco 技术提示约定。
本文档使用此图所示的网络设置。
注意:此配置中使用的IP编址方案在Internet上不能合法路由。这些地址是在实验室环境中使用的 RFC 1918 地址。
请完成以下步骤以创建 VPN 隧道:
打开浏览器并键入 https:// <Inside_IP_Address_of_ASA> 以访问 ASA 上的 ASDM。
请确保核准浏览器提供的有关 SSL 证书真实性的任何警告。默认的用户名和口令均为空。
ASA 显示此窗口以允许下载 ASDM 应用程序。此示例将应用程序加载到本地计算机,但不在 Java 小程序中运行。
单击 Download ASDM Launcher and Start ASDM 以下载 ASDM 应用程序的安装程序。
下载 ASDM 启动程序之后,完成提示所指示的步骤,以便安装该软件并运行 Cisco ASDM 启动程序。
输入使用 http - 命令配置的接口的 IP 地址,以及用户名和口令(如果已指定)。
此示例使用默认空白用户名和口令。
ASDM 应用程序连接到 ASA 后,请运行 VPN 向导。
选择 Site-to-Site IPsec VPN 隧道类型。
指定远程对等体的外部 IP 地址。输入要使用的身份验证信息,在本示例中是预共享密钥。
指定要用于 IKE 的属性,也称为“第 1 阶段”。这些属性在隧道两端必须是相同的。
指定要用于 IPsec 的属性,也称为“第 2 阶段”。这些属性在两端必须匹配。
指定应允许其数据流通过 VPN 隧道的主机。在此步骤中,指定 ASA1 的本地主机。
指定隧道的远程端的主机和网络。
此概要中显示了通过 VPN 向导定义的属性。仔细检查配置,如果您确保设置正确,请单击 Finish。
请完成以下步骤,以便在 Cisco 安全设备上配置 NTP:
在 ASDM 主页中选择 Configuration(如图所示):
现在选择 Properties > Device Management > NTP,以便打开 ASDM 的 NTP 配置页(如图所示):
单击 ADD 按钮添加 NTP 服务器,并在单击 ADD 按钮后显示的新窗口中提供所需属性,如 IP 地址、接口名称(内部或外部)以及用于身份验证的密钥编号和密钥值(如屏幕截图所示)。然后,单击 OK。
注意:对于ASA1,接口名称应选择为inside,对于ASA2,接口名称应选择为outside。
注意:ASA和NTP服务器中的ntp authentication key应相同。
CLI 中的 ASA1 和 ASA2 身份验证属性配置如下所示:
ASA1#ntp authentication-key 1 md5 cisco ntp trusted-key 1 ntp server 172.22.1.161 key 1 source inside
ASA2#ntp authentication-key 1 md5 cisco ntp trusted-key 1 ntp server 172.22.1.161 key 1 source outside
现在单击 Enable NTP Authentication 复选框,然后单击 Apply,即可完成 NTP 配置任务。
ASA1 |
---|
ASA#show run : Saved ASA Version 7.1(1) ! hostname ASA1 domain-name default.domain.invalid enable password 8Ry2YjIyt7RRXU24 encrypted names ! interface Ethernet0 nameif outside security-level 0 ip address 10.10.10.1 255.255.255.0 !--- Configure the outside interface. ! interface Ethernet1 nameif inside security-level 100 ip address 172.22.1.163 255.255.255.0 !--- Configure the inside interface. ! !-- Output suppressed ! passwd 2KFQnbNIdI.2KYOU encrypted ftp mode passive dns server-group DefaultDNS domain-name default.domain.invalid access-list inside_nat0_outbound extended permit ip 172.22.1.0 255.255.255.0 172 .16.1.0 255.255.255.0 !--- This access list (inside_nat0_outbound) is used !--- with the nat zero command. This prevents traffic which !--- matches the access list from undergoing network address translation (NAT). !--- The traffic specified by this ACL is traffic that is to be encrypted and !--- sent across the VPN tunnel. This ACL is intentionally !--- the same as (outside_cryptomap_20). !--- Two separate access lists should always be used in this configuration. access-list outside_cryptomap_20 extended permit ip 172.22.1.0 255.255.255.0 172 .16.1.0 255.255.255.0 !--- This access list (outside_cryptomap_20) is used !--- with the crypto map outside_map !--- to determine which traffic should be encrypted and sent !--- across the tunnel. !--- This ACL is intentionally the same as (inside_nat0_outbound). !--- Two separate access lists should always be used in this configuration. pager lines 24 mtu inside 1500 mtu outside 1500 no failover asdm image flash:/asdm-511.bin !--- Enter this command to specify the location of the ASDM image. asdm history enable arp timeout 14400 nat (inside) 0 access-list inside_nat0_outbound !--- NAT 0 prevents NAT for networks specified in !--- the ACL inside_nat0_outbound. route outside 0.0.0.0 0.0.0.0 10.10.10.2 1 timeout xlate 3:00:00 timeout conn 1:00:00 half-closed 0:10:00 udp 0:02:00 icmp 0:00:02 timeout sunrpc 0:10:00 h323 0:05:00 h225 1:00:00 mgcp 0:05:00 timeout mgcp-pat 0:05:00 sip 0:30:00 sip_media 0:02:00 timeout uauth 0:05:00 absolute http server enable !--- Enter this command in order to enable the HTTPS server !--- for ASDM. http 172.22.1.1 255.255.255.255 inside !--- Identify the IP addresses from which the security appliance !--- accepts HTTPS connections. no snmp-server location no snmp-server contact !--- PHASE 2 CONFIGURATION ---! !--- The encryption types for Phase 2 are defined here. crypto ipsec transform-set ESP-AES-256-SHA esp-aes-256 esp-sha-hmac !--- Define the transform set for Phase 2. crypto map outside_map 20 match address outside_cryptomap_20 !--- Define which traffic should be sent to the IPsec peer. crypto map outside_map 20 set peer 10.20.20.1 !--- Sets the IPsec peer crypto map outside_map 20 set transform-set ESP-AES-256-SHA !--- Sets the IPsec transform set "ESP-AES-256-SHA" !--- to be used with the crypto map entry "outside_map". crypto map outside_map interface outside !--- Specifies the interface to be used with !--- the settings defined in this configuration. !--- PHASE 1 CONFIGURATION ---! !--- This configuration uses isakmp policy 10. !--- Policy 65535 is included in the config by default. !--- The configuration commands here define the Phase !--- 1 policy parameters that are used. isakmp enable outside isakmp policy 10 authentication pre-share isakmp policy 10 encryption aes-256 isakmp policy 10 hash sha isakmp policy 10 group 5 isakmp policy 10 lifetime 86400 isakmp policy 65535 authentication pre-share isakmp policy 65535 encryption 3des isakmp policy 65535 hash sha isakmp policy 65535 group 2 isakmp policy 65535 lifetime 86400 tunnel-group 10.20.20.1 type ipsec-l2l !--- In order to create and manage the database of connection-specific !--- records for ipsec-l2l—IPsec (LAN-to-LAN) tunnels, use the command !--- tunnel-group in global configuration mode. !--- For L2L connections the name of the tunnel group MUST be the IP !--- address of the IPsec peer. tunnel-group 10.20.20.1 ipsec-attributes pre-shared-key * !--- Enter the pre-shared-key in order to configure the !--- authentication method. telnet timeout 5 ssh timeout 5 console timeout 0 ! class-map inspection_default match default-inspection-traffic ! ! policy-map global_policy class inspection_default inspect dns maximum-length 512 inspect ftp inspect h323 h225 inspect h323 ras inspect netbios inspect rsh inspect rtsp inspect skinny inspect esmtp inspect sqlnet inspect sunrpc inspect tftp inspect sip inspect xdmcp ! service-policy global_policy global !--- Define the NTP server autentication-key,Trusted-key !--- and the NTP server address for configuring NTP. ntp authentication-key 1 md5 * ntp trusted-key 1 !--- The NTP server source is to be mentioned as inside for ASA1 ntp server 172.22.1.161 key 1 source inside Cryptochecksum:ce7210254f4a0bd263a9072a4ccb7cf7 : end |
此视频已发布到 Cisco 支持社区 ,该视频通过演示说明了将 ASA 配置为 NTP 客户端的步骤:
如何将 Cisco 自适应安全设备 (ASA) 配置为与 Network Time Protocol (NTP) 服务器同步时钟。
ASA2 |
---|
ASA Version 7.1(1) ! hostname ASA2 domain-name default.domain.invalid enable password 8Ry2YjIyt7RRXU24 encrypted names ! interface Ethernet0 nameif outside security-level 0 ip address 10.20.20.1 255.255.255.0 ! interface Ethernet1 nameif inside security-level 100 ip address 172.16.1.1 255.255.255.0 ! passwd 2KFQnbNIdI.2KYOU encrypted ftp mode passive dns server-group DefaultDNS domain-name default.domain.invalid access-list inside_nat0_outbound extended permit ip 172.16.1.0 255.255.255.0 172 .22.1.0 255.255.255.0 !--- Note that this ACL is a mirror of the inside_nat0_outbound !--- ACL on ASA1. access-list outside_cryptomap_20 extended permit ip 172.16.1.0 255.255.255.0 172 .22.1.0 255.255.255.0 !--- Note that this ACL is a mirror of the outside_cryptomap_20 !--- ACL on ASA1. pager lines 24 mtu inside 1500 mtu outside 1500 no failover asdm image flash:/asdm-511.bin no asdm history enable arp timeout 14400 nat (inside) 0 access-list inside_nat0_outbound timeout xlate 3:00:00 timeout conn 1:00:00 half-closed 0:10:00 udp 0:02:00 icmp 0:00:02 timeout sunrpc 0:10:00 h323 0:05:00 h225 1:00:00 mgcp 0:05:00 timeout mgcp-pat 0:05:00 sip 0:30:00 sip_media 0:02:00 timeout uauth 0:05:00 absolute http server enable http 0.0.0.0 0.0.0.0 inside no snmp-server location no snmp-server contact crypto ipsec transform-set ESP-AES-256-SHA esp-aes-256 esp-sha-hmac crypto map outside_map 20 match address outside_cryptomap_20 crypto map outside_map 20 set peer 10.10.10.1 crypto map outside_map 20 set transform-set ESP-AES-256-SHA crypto map outside_map interface outside isakmp enable outside isakmp policy 10 authentication pre-share isakmp policy 10 encryption aes-256 isakmp policy 10 hash sha isakmp policy 10 group 5 isakmp policy 10 lifetime 86400 tunnel-group 10.10.10.1 type ipsec-l2l tunnel-group 10.10.10.1 ipsec-attributes pre-shared-key * telnet timeout 5 ssh timeout 5 console timeout 0 ! class-map inspection_default match default-inspection-traffic ! ! policy-map global_policy class inspection_default inspect dns maximum-length 512 inspect ftp inspect h323 h225 inspect h323 ras inspect netbios inspect rsh inspect rtsp inspect skinny inspect esmtp inspect sqlnet inspect sunrpc inspect tftp inspect sip inspect xdmcp ! service-policy global_policy global !--- Define the NTP server autentication-key,Trusted-key !--- and the NTP server address for configuring NTP. ntp authentication-key 1 md5 * ntp trusted-key 1 !--- The NTP server source is to be mentioned as outside for ASA2. ntp server 172.22.1.161 key 1 source outside Cryptochecksum:d5e2ee898f5e8bd28e6f027aeed7f41b : end ASA# |
本部分提供的信息可帮助您确认您的配置是否可正常运行。
命令输出解释程序工具(仅限注册用户)支持某些 show 命令,使用此工具可以查看对 show 命令输出的分析。
show ntp status - 显示 NTP 时钟信息。
ASA1#show ntp status Clock is synchronized, stratum 2, reference is 172.22.1.161 nominal freq is 99.9984 Hz, actual freq is 99.9983 Hz, precision is 2**6 reference time is ccf22b77.f7a6e7b6 (13:28:23.967 UTC Tue Dec 16 2008) clock offset is 34.8049 msec, root delay is 4.78 msec root dispersion is 60.23 msec, peer dispersion is 25.41 msec
show ntp associations [detail] - 显示配置的网络时间服务器关联。
ASA1#show ntp associations detail 172.22.1.161 configured, authenticated, our_master, sane, valid, stratum 1 ref ID .LOCL., time ccf2287d.3668b946 (13:15:41.212 UTC Tue Dec 16 2008) our mode client, peer mode server, our poll intvl 64, peer poll intvl 64 root delay 0.00 msec, root disp 0.03, reach 7, sync dist 23.087 delay 4.52 msec, offset 9.7649 msec, dispersion 20.80 precision 2**19, version 3 org time ccf22896.f1a4fca3 (13:16:06.943 UTC Tue Dec 16 2008) rcv time ccf22896.efb94b28 (13:16:06.936 UTC Tue Dec 16 2008) xmt time ccf22896.ee5691dc (13:16:06.931 UTC Tue Dec 16 2008) filtdelay = 4.52 4.68 4.61 0.00 0.00 0.00 0.00 0.00 filtoffset = 9.76 7.09 3.85 0.00 0.00 0.00 0.00 0.00 filterror = 15.63 16.60 17.58 14904.3 14904.3 14904.3 14904.3 14904.3
本部分提供的信息可用于对配置进行故障排除。
命令输出解释程序工具(仅限注册用户)支持某些 show 命令,使用此工具可以查看对 show 命令输出的分析。
注意:在发出debug命令之前,请参阅有关Debug命令的重要信息。
debug ntp validity - 显示 NTP 对等体时钟有效性。
以下是密钥不匹配的 debug 输出:
NTP: packet from 172.22.1.161 failed validity tests 10 Authentication failed
debug ntp packet - 显示 NTP 数据包信息。
当没有来自服务器的响应时,在 ASA 上只能看到 NTP xmit 数据包,而看不到 NTP rcv 数据包。
ASA1# NTP: xmit packet to 172.22.1.161: leap 0, mode 3, version 3, stratum 2, ppoll 64 rtdel 012b (4.562), rtdsp 0cb6 (49.652), refid ac1601a1 (172.22.1.161) ref ccf22916.f1211384 (13:18:14.941 UTC Tue Dec 16 2008) org ccf22916.f426232d (13:18:14.953 UTC Tue Dec 16 2008) rec ccf22916.f1211384 (13:18:14.941 UTC Tue Dec 16 2008) xmt ccf22956.f08ee8b4 (13:19:18.939 UTC Tue Dec 16 2008) NTP: rcv packet from 172.22.1.161 to 172.22.1.163 on inside: leap 0, mode 4, version 3, stratum 1, ppoll 64 rtdel 0000 (0.000), rtdsp 0002 (0.031), refid 4c4f434c (76.79.67.76) ref ccf2293d.366a4808 (13:18:53.212 UTC Tue Dec 16 2008) org ccf22956.f08ee8b4 (13:19:18.939 UTC Tue Dec 16 2008) rec ccf22956.f52e480e (13:19:18.957 UTC Tue Dec 16 2008) xmt ccf22956.f5688c29 (13:19:18.958 UTC Tue Dec 16 2008) inp ccf22956.f982bcd9 (13:19:18.974 UTC Tue Dec 16 2008)
版本 | 发布日期 | 备注 |
---|---|---|
1.0 |
16-Dec-2008 |
初始版本 |