两条IPsec隧道之间的强天鹅转发业务

Question

给定具有外部静态IP的StrongSwan IKEv2设置的远程(集中式) VPN服务器：

• 集中式服务器内部IP 192.168.1.65，网络192.168.1.64/27

和两个为内部网络做NAT的网关：

• 第一网关内部IP 192.168.1.33，网络: 192.168.1.32/27；
• 第二网关内部IP 192.168.1.1，网络: 192.168.1.0/27；

网关也使用StrongSwan连接到集中式服务器。

连接从网关到服务器，从服务器到网关都能很好地工作: ping工作，访问服务器/网关上的服务。网关后面的设备也可以无问题地访问服务器。

当我试图访问不同网关之间的计算机时，问题就开始了。

Configurations:

集中：

conn base
    keyexchange = ikev2
    keyingtries = %forever
    forceencaps = yes
    compress = no

    left = centralized
    leftid = @centralized
    leftauth = pubkey
    leftca = "..."
    leftcert = centralized.crt
    leftupdown = sudo -E ipsec _updown iptables
    leftsubnet = 192.168.1.65

    right = %any
    rightauth = pubkey
    rightauth2 = psk
    rightca = %same

conn gateway-first
    auto = add
    rightid = @gateway-first
    rightcert = gateway-first.crt
    rightsubnet = 192.168.1.32/27
    rightsourceip = 192.168.1.66
    also = base

conn gateway-second
    auto = add
    rightid = @gateway-second
    rightcert = gateway-second.crt
    rightsubnet = 192.168.1.0/27
    rightsourceip = 192.168.1.67
    also = base

网关-首先：

conn gateway-first
    auto = route
    dpdaction = restart
    closeaction = restart
    keyexchange = ikev2
    keyingtries = %forever
    forceencaps = yes
    compress = no

    rightid = @centralized
    right = centralized
    rightauth = pubkey
    rightca = "..."
    rightcert = centralized.crt
    rightsubnet = 192.168.1.65,192.168.1.0/27

    leftid = @gateway-first
    left = %defaultroute
    leftauth = pubkey
    leftauth2 = psk
    leftca = %same
    leftcert = gateway-first.crt
    leftupdown = sudo -E ipsec _updown iptables
    leftsubnet = 192.168.1.32/27
    leftsourceip = %config4

网关-第二步：

conn gateway-second
    auto = route
    dpdaction = restart
    closeaction = restart
    keyexchange = ikev2
    keyingtries = %forever
    forceencaps = yes
    compress = no

    rightid = @centralized
    right = centralized
    rightauth = pubkey
    rightca = "..."
    rightcert = centralized.crt
    rightsubnet = 192.168.1.65,192.168.1.32/27

    leftid = @gateway-second
    left = %defaultroute
    leftauth = pubkey
    leftauth2 = psk
    leftca = %same
    leftcert = gateway-second.crt
    leftupdown = sudo -E ipsec _updown iptables
    leftsubnet = 192.168.1.1/27
    leftsourceip = %config4

当试图从网关后面的计算机第二次打开网关时(源计算机IP为192.168.1.40)，同时在集中服务器上运行tcpdump显示：

tcpdump -i eth0 host 192.168.1.1 -n
error : ret -1
tcpdump: verbose output suppressed, use -v or -vv for full protocol decode
listening on eth0, link-type EN10MB (Ethernet), capture size 262144 bytes
21:27:49.030650 IP 192.168.1.40 > 192.168.1.1: ICMP echo request, id 9721, seq 35, length 64
21:27:50.026652 IP 192.168.1.40 > 192.168.1.1: ICMP echo request, id 9721, seq 36, length 64
21:27:51.031805 IP 192.168.1.40 > 192.168.1.1: ICMP echo request, id 9721, seq 37, length 64
21:27:52.041165 IP 192.168.1.40 > 192.168.1.1: ICMP echo request, id 9721, seq 38, length 64
21:27:53.029530 IP 192.168.1.40 > 192.168.1.1: ICMP echo request, id 9721, seq 39, length 64

因此，根据这个日志数据包到达集中服务器，但从未转发到192.168.1.1。

在集中式服务器和两个网关上，我启用了转发：

net.ipv4.ip_forward = 1

集中式服务器上的路由表：

# ip route
default via yy.yy.yy.yy dev eth0  proto static 
zz.zz.zz.zz dev eth0  proto kernel  scope link  src xx.xx.xx.xx
192.168.1.64/27 via 192.168.1.65 dev eth1  proto static

还有路由表#220 (VPN)：

# ip route show table 220
192.168.1.0/27 via 5.189.141.1 dev eth0  proto static  src 192.168.1.65 
192.168.1.32/27 via 5.189.141.1 dev eth0  proto static  src 192.168.1.65 

有什么办法可以在两个不同的隧道之间进行转发吗？

Answer 1

尝试将这两个网关的子网添加到中央服务器上的leftsubnet。即使每个网关上的rightsubnet包含各自相反的子网，流量选择器也将缩小到中心服务器上配置为leftsubnet (即192.168.1.65)的范围。您应该在ipsec statusall的输出中看到这一点。您还可以在中央服务器上配置leftsubnet=0.0.0.0/0，然后它将接受网关建议的任何作为其rightsubnet的内容。