孔凡安,VRF场景下DNAT+SNAT典型配置举例

组网及说明

注：如无特别说明，描述中的 FW1 或 MSR1 对应拓扑中设备名称末尾数字为 1 的设备，FW2 或 MSR2 对应拓扑中设备名称末尾数字为 2 的设备，以此类推；另外，同一网段中，IP 地址的主机位为其设备编号，如 FW1 的 g0/0 接口若在 1.1.1.0/24 网段，则其 IP 地址为 1.1.1.1/24，以此类推。

实验说明：

1. FW1位于公网侧，通过SSH访问内网服务器（FW3代替）。

2. FW2未NAT设备，GE1/0/0位于untrust安全域，vpn实例为v1；GE1/0/1位于trust安全域，vpn实例为v2。

3. FW上GE1/0/0配置内部服务器映射DNAT，GE1/0/1配置SNAT。

4. FW1和FW3的配置略过。

配置步骤

1. VPN实例

# 

ip vpn-instance v1 

# 

ip vpn-instance v2

2. NAT相关配置

# 

NAT address-group 1 address 10.1.1.12 10.1.1.12 

#

acl advanced 3001

 rule 0 permit ip vpn-instance v1 source 1.1.1.1 0

3. 接口配置

#

interface GigabitEthernet1/0/0

 port link-mode route

 combo enable copper

 ip binding vpn-instance v1

 ip address 1.1.1.2 255.255.255.0

 nat server protocol tcp global 1.1.1.12 22 vpn-instance v1 inside 10.1.1.3 22 vpn-instance v2

#

interface GigabitEthernet1/0/1

 port link-mode route

 combo enable copper

 ip binding vpn-instance v2

 ip address 10.1.1.2 255.255.255.0

 nat outbound 3001 address-group 1 vpn-instance v2

 4. 安全策略

security-policy ip

 rule 1 name u2t

  action pass

  VRF v2

  source-zone untrust

  destination-zone trust

  source-ip src

  destination-ip dst-v2

#

object-group ip address dst-v2

 0 network host address 10.1.1.3

#

object-group ip address src

 0 network host address 1.1.1.1

#

security-zone name Trust

 import interface GigabitEthernet1/0/1

#

security-zone name Untrust

 import interface GigabitEthernet1/0/0

会话信息：

Slot 1:

Initiator:

  Source      IP/port: 1.1.1.1/3078

  Destination IP/port: 1.1.1.12/22

  DS-Lite tunnel peer: -

  VPN instance/VLAN ID/Inline ID: v1/-/-

  Protocol: TCP(6)

  Inbound interface: GigabitEthernet1/0/0

  Source security zone: Untrust

Responder:

  Source      IP/port: 10.1.1.3/22

  Destination IP/port: 10.1.1.12/1029

  DS-Lite tunnel peer: -

  VPN instance/VLAN ID/Inline ID: v2/-/-

  Protocol: TCP(6)

  Inbound interface: GigabitEthernet1/0/1

  Source security zone: Trust

State: TCP_ESTABLISHED

Application: SSH

Rule ID: 1

Rule name: u2t

Start time: 2022-10-05 12:25:44  TTL: 1186s

Initiator->Responder:            8 packets       1241 bytes

Responder->Initiator:            7 packets       1413 bytes

Debug信息：

*Oct  5 12:25:44:786 2022 H3C IPFW/7/IPFW_PACKET: -COntext=1;

Receiving, interface = GigabitEthernet1/0/0

version = 4, headlen = 20, tos = 192

pktlen = 60, pktid = 51, offset = 0, ttl = 255, protocol = 6

checksum = 46778, s = 1.1.1.1, d = 1.1.1.12

channelID = 0, vpn-InstanceIn = 1, vpn-InstanceOut = 1.

prompt: Receiving IP packet from interface GigabitEthernet1/0/0.

Payload: TCP

  source port = 3078, destination port = 22

  sequence num = 0x048f6653, acknowledgement num = 0x00000000, flags = 0x2

  window size = 64512, checksum = 0x1a70, header length = 40.

*Oct  5 12:25:44:787 2022 H3C NAT/7/COMMON: -COntext=1;

 PACKET: (GigabitEthernet1/0/0-in-config) Protocol: TCP

         1.1.1.1: 3078 -        1.1.1.12:   22(VPN:    1) ------>

         1.1.1.1: 3078 -        10.1.1.3:   22(VPN:    2)

*Oct  5 12:25:44:787 2022 H3C NAT/7/COMMON: -COntext=1;

 PACKET: (GigabitEthernet1/0/1-out-config) Protocol: TCP

         1.1.1.1: 3078 -        10.1.1.3:   22(VPN:    1) ------>

       10.1.1.12: 1029 -        10.1.1.3:   22(VPN:    2)

*Oct  5 12:25:44:787 2022 H3C IPFW/7/IPFW_PACKET: -COntext=1;

Sending, interface = GigabitEthernet1/0/1

version = 4, headlen = 20, tos = 192

pktlen = 60, pktid = 51, offset = 0, ttl = 254, protocol = 6

checksum = 42424, s = 10.1.1.12, d = 10.1.1.3

channelID = 0, vpn-InstanceIn = 2, vpn-InstanceOut = 2.

prompt: Sending IP packet received from interface GigabitEthernet1/0/0 at interface GigabitEthernet1/0/1.

Payload: TCP

  source port = 1029, destination port = 22

  sequence num = 0x048f6653, acknowledgement num = 0x00000000, flags = 0x2

  window size = 64512, checksum = 0x106f, header length = 40.

*Oct  5 12:25:44:787 2022 H3C IPFW/7/IPFW_PACKET: -COntext=1;

Receiving, interface = GigabitEthernet1/0/1

version = 4, headlen = 20, tos = 192

pktlen = 60, pktid = 49, offset = 0, ttl = 255, protocol = 6

checksum = 42170, s = 10.1.1.3, d = 10.1.1.12

channelID = 0, vpn-InstanceIn = 2, vpn-InstanceOut = 2.

prompt: Receiving IP packet from interface GigabitEthernet1/0/1.

Payload: TCP

  source port = 22, destination port = 1029

  sequence num = 0x7fd759cc, acknowledgement num = 0x048f6654, flags = 0x12

  window size = 64512, checksum = 0x9270, header length = 40.

*Oct  5 12:25:44:787 2022 H3C NAT/7/COMMON: -COntext=1;

 PACKET: (GigabitEthernet1/0/1-in-session) Protocol: TCP

        10.1.1.3:   22 -       10.1.1.12: 1029(VPN:    2) ------>

        10.1.1.3:   22 -         1.1.1.1: 3078(VPN:    1)

*Oct  5 12:25:44:787 2022 H3C NAT/7/COMMON: -COntext=1;

 PACKET: (GigabitEthernet1/0/0-out-session) Protocol: TCP

        10.1.1.3:   22 -         1.1.1.1: 3078(VPN:    2) ------>

        1.1.1.12:   22 -         1.1.1.1: 3078(VPN:    1)

*Oct  5 12:25:44:787 2022 H3C IPFW/7/IPFW_PACKET: -COntext=1;

Sending, interface = GigabitEthernet1/0/0

version = 4, headlen = 20, tos = 192

pktlen = 60, pktid = 49, offset = 0, ttl = 254, protocol = 6

checksum = 47036, s = 1.1.1.12, d = 1.1.1.1

channelID = 0, vpn-InstanceIn = 1, vpn-InstanceOut = 1.

prompt: Sending IP packet received from interface GigabitEthernet1/0/1 at interface GigabitEthernet1/0/0.

Payload: TCP

  source port = 22, destination port = 3078

  sequence num = 0x7fd759cc, acknowledgement num = 0x048f6654, flags = 0x12

  window size = 64512, checksum = 0x9c71, header length = 40.

配置关键点

正常情况下，如果只配置了DNAT，需要添加VRF路由：

ip route-static vpn-instance v2 1.1.1.0 24 vpn-instance v1 1.1.1.1

配置了SNAT后，该路由可以取消。

注意事项：接口下NAT映射配置，以及SNAT对应的acl配置。