OpenVPN server. Traffic not routing to internal resources from OpenVpn clients

Hello, I try to setup OpenVPN server to make internal services available from external users (openVpn clients).

But I cannot reach any internal resources. I might be missing something, but this is just as basic as possible I could go, but still traffic is not routed to internal resources.

// Release version: 1.4-rolling-202403221102

$ show interfaces
Codes: S - State, L - Link, u - Up, D - Down, A - Admin Down
Interface    IP Address       MAC                VRF        MTU  S/L    Description
-----------  ---------------  -----------------  -------  -----  -----  ------------------
eth0         100.100.100.100/32  de:00:00:12:ed:6f  default   1500  u/u
eth1         172.16.4.7/22    02:00:00:12:00:e7  default   1500  u/u
lo           127.0.0.1/8      00:00:00:00:00:00  default  65536  u/u
             ::1/128
vtun10       10.23.32.1/32    n/a                default   1500  u/u

$ route -v
Kernel IP routing table
Destination     Gateway         Genmask         Flags Metric Ref    Use Iface
default         one-gw-to-rule- 0.0.0.0         UG    0      0        0 eth0
10.23.32.0      10.23.32.2      255.255.255.0   UG    0      0        0 vtun10
10.23.32.2      0.0.0.0         255.255.255.255 UH    0      0        0 vtun10
one-gw-to-rule- 0.0.0.0         255.255.255.255 UH    0      0        0 eth0
172.16.4.0      0.0.0.0         255.255.252.0   U     0      0        0 eth1


$ ping 172.16.4.11
PING 172.16.4.11 (172.16.4.11) 56(84) bytes of data.
64 bytes from 172.16.4.11: icmp_seq=1 ttl=64 time=0.848 ms
64 bytes from 172.16.4.11: icmp_seq=2 ttl=64 time=0.619 ms

$ arp -a
one-gw-to-rule- (62.210.0.1) at de:00:00:12:ed:70 [ether] on eth0
? (172.16.4.10) at 02:00:00:13:a8:9c [ether] on eth1
? (172.16.4.8) at 02:00:00:27:ee:e3 [ether] on eth1
? (172.16.4.2) at <incomplete> on eth1
? (172.16.4.6) at 02:00:00:16:f3:9f [ether] on eth1
? (172.16.4.9) at 02:00:00:19:5e:53 [ether] on eth1
? (172.16.4.11) at 02:00:00:1b:ba:a6 [ether] on eth1
? (169.254.169.254) at 00:00:22:05:ca:1e [ether] on eth1
? (172.16.4.3) at 02:00:00:19:95:75 [ether] on eth1

$ show openvpn server

OpenVPN status on vtun10

Client CN     Remote Host           Tunnel IP    Local Host    TX bytes    RX bytes    Connected Since
------------  --------------------  -----------  ------------  ----------  ----------  -------------------
user-1  5.5.5.5:44492  10.23.32.6   N/A           5.3 KB      5.4 KB      2025-02-26 07:43:55

configuration

firewall {
    ipv4 {
        input {
            filter {
                default-action "drop"
                default-log
                rule 10 {
                    action "accept"
                    protocol "tcp"
                    state "established"
                    state "related"
                }
                rule 20 {
                    action "accept"
                    protocol "icmp"
                }
                rule 30 {
                    action "accept"
                    protocol "udp"
                    source {
                        port "53"
                    }
                }
                rule 50 {
                    action "accept"
                    description "OpenVPN server"
                    destination {
                        port "1194"
                    }
                    protocol "udp"
                }
                rule 1000 {
                    action "accept"
                    description "Allow SSH"
                    destination {
                        port "22"
                    }
                    protocol "tcp"
                    source {
                        address "100.100.100.100/32"
                    }
                }
                rule 1010 {
                    action "accept"
                    description "Allow all from LAN"
                    protocol "tcp"
                    source {
                        address "172.16.4.0/22"
                    }
                }
                rule 1050 {
                    action "accept"
                    description "Allow all from OpenVPN subnet"
                    source {
                        address "10.23.32.0/24"
                    }
                }
            }
        }
    }
}

interfaces {
    ethernet eth0 {
        address "dhcp"
    }
    ethernet eth1 {
        address "dhcp"
    }
    loopback lo {
    }
    openvpn vtun10 {
        encryption {
            cipher "aes256"
        }
        hash "sha512"
        local-port "1194"
        mode "server"
        openvpn-option "duplicate-cn"
        persistent-tunnel
        protocol "udp"
        server {
            push-route 172.16.4.0/22 {
            }
            subnet "10.23.32.0/24"
        }
        tls {
            ca-certificate "ca-1"
            certificate "srv-1"
            dh-params "dh-1"
        }
    }
}

When try to ping a device behind eth0 - timeouts, but can ping eth0 interface IP.

[from client, when connected to vyos router]

❯ ping 172.16.4.7
PING 172.16.4.7 (172.16.4.7): 56 data bytes
64 bytes from 172.16.4.7: icmp_seq=0 ttl=64 time=116.502 ms
64 bytes from 172.16.4.7: icmp_seq=1 ttl=64 time=299.593 ms
64 bytes from 172.16.4.7: icmp_seq=2 ttl=64 time=203.667 ms
^C
--- 172.16.4.7 ping statistics ---
3 packets transmitted, 3 packets received, 0.0% packet loss
round-trip min/avg/max/stddev = 116.502/206.587/299.593/74.775 ms
❯ ping 172.16.4.11
PING 172.16.4.11 (172.16.4.11): 56 data bytes
Request timeout for icmp_seq 0
Request timeout for icmp_seq 1
^C
--- 172.16.4.11 ping statistics ---
3 packets transmitted, 0 packets received, 100.0% packet loss

Could anyone point me to what I’m missing here? Ty!

Does 172.16.4.11 know how to route back to 10.23.32.0/24?
That is, what’s the default route of 172.16.4.11? I assume it’s 172.16.4.7?

Sounds like a problem with the return traffic path. What do you see if you run a tcpdump host <ip address of your openvpn client> ?

As you speak - there must be an issue with default route, the host 172.16.4.11 has default route to 172.16.4.2.

So there is no issues with VyOS or OpenVPN.

Thanks.

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