Article 6DD7A Client connected to the OpenVPN server, but can't see the internal network

Client connected to the OpenVPN server, but can't see the internal network

by
Jason.nix
from LinuxQuestions.org on (#6DD7A)
Hello,
My OpenVPN server NICs are:
Code:enp0s3 (NAT)
enp0s8 (LAN)And their IP addresses are:
Code:# ifconfig
enp0s3: flags=4163<UP,BROADCAST,RUNNING,MULTICAST> mtu 1500
inet 10.0.2.15 netmask 255.255.255.0 broadcast 10.0.2.255
inet6 fe80::a00:27ff:feed:b47c prefixlen 64 scopeid 0x20<link>
ether 08:00:27:ed:b4:7c txqueuelen 1000 (Ethernet)
RX packets 21328 bytes 5784129 (5.5 MiB)
RX errors 0 dropped 0 overruns 0 frame 0
TX packets 14787 bytes 2805600 (2.6 MiB)
TX errors 0 dropped 0 overruns 0 carrier 0 collisions 0

enp0s8: flags=4163<UP,BROADCAST,RUNNING,MULTICAST> mtu 1500
inet 192.168.1.20 netmask 255.255.255.0 broadcast 192.168.1.255
inet6 fe80::a00:27ff:fe74:6397 prefixlen 64 scopeid 0x20<link>
ether 08:00:27:74:63:97 txqueuelen 1000 (Ethernet)
RX packets 9853 bytes 1811888 (1.7 MiB)
RX errors 0 dropped 0 overruns 0 frame 0
TX packets 3657 bytes 1472226 (1.4 MiB)
TX errors 0 dropped 0 overruns 0 carrier 0 collisions 0My OpenVPN server can ping my internal network:
Code:# ping 172.20.1.18
PING 172.20.1.18 (172.20.1.18) 56(84) bytes of data.
64 bytes from 172.20.1.18: icmp_seq=1 ttl=63 time=1.10 ms
64 bytes from 172.20.1.18: icmp_seq=2 ttl=63 time=0.954 ms
64 bytes from 172.20.1.18: icmp_seq=3 ttl=63 time=1.21 ms
^C
--- 172.20.1.18 ping statistics ---
3 packets transmitted, 3 received, 0% packet loss, time 2054ms
rtt min/avg/max/mdev = 0.954/1.089/1.214/0.106 msI want to connect a windows client to this server so that it can see my internal network. My OpenVPN server configuration file is:
Code:port 1194
proto udp
dev tun0
ca ca.crt
cert server.crt
key server.key
dh dh.pem
server 10.8.0.0 255.255.255.0
push "redirect-gateway def1 bypass-dhcp"
route 172.20.1.0 255.255.0.0
push "route 172.20.1.0 255.255.0.0"
push "dhcp-option DNS 172.20.1.2" # My internal network DNS server IP
keepalive 10 120
tls-auth ta.key 0
data-ciphers AES-256-CBC
user nobody
group nogroup
persist-key
persist-tun
status /var/log/openvpn/openvpn-status.log
log /var/log/openvpn/openvpn.log
log-append /var/log/openvpn/openvpn.log
verb 3
explicit-exit-notify 1On OpenVPN server I did the following iptables rules:
Code:# IF_MAIN=enp0s3
# IF_TUNNEL=tun0
# YOUR_OPENVPN_SUBNET=10.8.0.0/16
# iptables -I INPUT -p udp --dport 1194 -j ACCEPT
# iptables -A FORWARD -i $IF_MAIN -o $IF_TUNNEL -m state --state ESTABLISHED,RELATED -j ACCEPT
# iptables -A FORWARD -s $YOUR_OPENVPN_SUBNET -o $IF_MAIN -j ACCEPT
# iptables -t nat -A POSTROUTING -s $YOUR_OPENVPN_SUBNET -o $IF_MAIN -j MASQUERADEThen, I disable the IP forwarding:
Code:# sysctl -p
net.ipv4.ip_forward = 0And the client.ovpn file is:
Code:dev tun
proto udp
remote 192.168.1.20 1194
route add 172.20.1.0 255.255.0.0
resolv-retry infinite
nobind
persist-key
persist-tun
ca ca.crt
cert client.crt
key client.key
remote-cert-tls server
tls-auth ta.key 1
data-ciphers AES-256-CBC
verb 3When I connected to the OpenVPN server, then I got the following message:
Code:Sun Jul 30 16:25:01 2023 Note: --cipher is not set. OpenVPN versions before 2.5 defaulted to BF-CBC as fallback when cipher negotiation failed in this case. If you need this fallback please add '--data-ciphers-fallback BF-CBC' to your configuration and/or add BF-CBC to --data-ciphers.
Sun Jul 30 16:25:01 2023 Note: cipher 'AES-256-CBC' in --data-ciphers is not supported by ovpn-dco, disabling data channel offload.
Sun Jul 30 16:25:01 2023 OpenVPN 2.6.5 [git:v2.6.5/cbc9e0ce412e7b42] Windows-MSVC [SSL (OpenSSL)] [LZO] [LZ4] [PKCS11] [AEAD] [DCO] built on Jun 13 2023
Sun Jul 30 16:25:01 2023 Windows version 6.1 (Windows 7), amd64 executable
Sun Jul 30 16:25:01 2023 library versions: OpenSSL 3.1.1 30 May 2023, LZO 2.10
Sun Jul 30 16:25:01 2023 DCO version: v0
Sun Jul 30 16:25:01 2023 MANAGEMENT: TCP Socket listening on [AF_INET]127.0.0.1:25342
Sun Jul 30 16:25:01 2023 Need hold release from management interface, waiting...
Sun Jul 30 16:25:01 2023 MANAGEMENT: Client connected from [AF_INET]127.0.0.1:1095
Sun Jul 30 16:25:01 2023 MANAGEMENT: CMD 'state on'
Sun Jul 30 16:25:01 2023 MANAGEMENT: CMD 'log on all'
Sun Jul 30 16:25:01 2023 MANAGEMENT: CMD 'echo on all'
Sun Jul 30 16:25:01 2023 MANAGEMENT: CMD 'bytecount 5'
Sun Jul 30 16:25:01 2023 MANAGEMENT: CMD 'state'
Sun Jul 30 16:25:01 2023 MANAGEMENT: CMD 'hold off'
Sun Jul 30 16:25:01 2023 MANAGEMENT: CMD 'hold release'
Sun Jul 30 16:25:02 2023 TCP/UDP: Preserving recently used remote address: [AF_INET]192.168.1.20:1194
Sun Jul 30 16:25:02 2023 Socket Buffers: R=[8192->8192] S=[8192->8192]
Sun Jul 30 16:25:02 2023 UDPv4 link local: (not bound)
Sun Jul 30 16:25:02 2023 UDPv4 link remote: [AF_INET]192.168.1.20:1194
Sun Jul 30 16:25:02 2023 MANAGEMENT: >STATE:1690718102,WAIT,,,,,,
Sun Jul 30 16:25:02 2023 MANAGEMENT: >STATE:1690718102,AUTH,,,,,,
Sun Jul 30 16:25:02 2023 TLS: Initial packet from [AF_INET]192.168.1.20:1194, sid=859b58ea 7fe7a961
Sun Jul 30 16:25:02 2023 VERIFY OK: depth=1, CN=Server
Sun Jul 30 16:25:02 2023 VERIFY KU OK
Sun Jul 30 16:25:02 2023 Validating certificate extended key usage
Sun Jul 30 16:25:02 2023 ++ Certificate has EKU (str) TLS Web Server Authentication, expects TLS Web Server Authentication
Sun Jul 30 16:25:02 2023 VERIFY EKU OK
Sun Jul 30 16:25:02 2023 VERIFY OK: depth=0, CN=server
Sun Jul 30 16:25:02 2023 Control Channel: TLSv1.3, cipher TLSv1.3 TLS_AES_256_GCM_SHA384, peer certificate: 2048 bit RSA, signature: RSA-SHA256
Sun Jul 30 16:25:02 2023 [server] Peer Connection Initiated with [AF_INET]192.168.1.20:1194
Sun Jul 30 16:25:02 2023 TLS: move_session: dest=TM_ACTIVE src=TM_INITIAL reinit_src=1
Sun Jul 30 16:25:02 2023 TLS: tls_multi_process: initial untrusted session promoted to trusted
Sun Jul 30 16:25:02 2023 PUSH: Received control message: 'PUSH_REPLY,redirect-gateway def1 bypass-dhcp,route 172.20.1.0 255.255.0.0,dhcp-option DNS 172.20.1.2,dhcp-option DNS 172.20.1.7,route 10.8.0.1,topology net30,ping 10,ping-restart 120,ifconfig 10.8.0.6 10.8.0.5,peer-id 1,cipher AES-256-CBC,protocol-flags cc-exit tls-ekm dyn-tls-crypt,tun-mtu 1500'
Sun Jul 30 16:25:02 2023 OPTIONS IMPORT: --ifconfig/up options modified
Sun Jul 30 16:25:02 2023 OPTIONS IMPORT: route options modified
Sun Jul 30 16:25:02 2023 OPTIONS IMPORT: --ip-win32 and/or --dhcp-option options modified
Sun Jul 30 16:25:02 2023 OPTIONS IMPORT: tun-mtu set to 1500
Sun Jul 30 16:25:02 2023 interactive service msg_channel=312
Sun Jul 30 16:25:02 2023 open_tun
Sun Jul 30 16:25:02 2023 tap-windows6 device [OpenVPN TAP-Windows6] opened
Sun Jul 30 16:25:02 2023 TAP-Windows Driver Version 9.24
Sun Jul 30 16:25:02 2023 Notified TAP-Windows driver to set a DHCP IP/netmask of 10.8.0.6/255.255.255.252 on interface {6A2BF0FA-B68E-4062-9447-B078773E36FD} [DHCP-serv: 10.8.0.5, lease-time: 31536000]
Sun Jul 30 16:25:02 2023 Successful ARP Flush on interface [15] {6A2BF0FA-B68E-4062-9447-B078773E36FD}
Sun Jul 30 16:25:02 2023 MANAGEMENT: >STATE:1690718102,ASSIGN_IP,,10.8.0.6,,,,
Sun Jul 30 16:25:02 2023 IPv4 MTU set to 1500 on interface 15 using service
Sun Jul 30 16:25:02 2023 Data Channel: cipher 'AES-256-CBC', auth 'SHA1', peer-id: 1
Sun Jul 30 16:25:02 2023 Timers: ping 10, ping-restart 120
Sun Jul 30 16:25:02 2023 Protocol options: protocol-flags cc-exit tls-ekm dyn-tls-crypt
Sun Jul 30 16:25:07 2023 TEST ROUTES: 4/4 succeeded len=3 ret=1 a=0 u/d=up
Sun Jul 30 16:25:07 2023 C:\Windows\system32\route.exe ADD 192.168.1.20 MASK 255.255.255.255 192.168.1.20 IF 11
Sun Jul 30 16:25:07 2023 Route addition via service succeeded
Sun Jul 30 16:25:07 2023 C:\Windows\system32\route.exe ADD 0.0.0.0 MASK 128.0.0.0 10.8.0.5
Sun Jul 30 16:25:07 2023 Route addition via service succeeded
Sun Jul 30 16:25:07 2023 C:\Windows\system32\route.exe ADD 128.0.0.0 MASK 128.0.0.0 10.8.0.5
Sun Jul 30 16:25:07 2023 Route addition via service succeeded
Sun Jul 30 16:25:07 2023 MANAGEMENT: >STATE:1690718107,ADD_ROUTES,,,,,,
Sun Jul 30 16:25:07 2023 C:\Windows\system32\route.exe ADD 172.20.1.0 MASK 255.255.0.0 10.8.0.5
Sun Jul 30 16:25:07 2023 ERROR: route addition failed using service: The parameter is incorrect. [status=87 if_index=15]
Sun Jul 30 16:25:07 2023 C:\Windows\system32\route.exe ADD 172.20.1.0 MASK 255.255.0.0 10.8.0.5
Sun Jul 30 16:25:07 2023 ERROR: route addition failed using service: The parameter is incorrect. [status=87 if_index=15]
Sun Jul 30 16:25:07 2023 C:\Windows\system32\route.exe ADD 10.8.0.1 MASK 255.255.255.255 10.8.0.5
Sun Jul 30 16:25:07 2023 Route addition via service succeeded
Sun Jul 30 16:25:07 2023 Initialization Sequence Completed
Sun Jul 30 16:25:07 2023 MANAGEMENT: >STATE:1690718107,CONNECTED,ROUTE_ERROR,10.8.0.6,192.168.1.20,1194,,
Sun Jul 30 16:25:07 2023 ERROR: Some routes were not successfully added. The connection may not function correctlyClient connected to the server:
Code:Unknown adapter OpenVPN TAP-Windows6:

Connection-specific DNS Suffix . :
Description . . . . . . . . . . . : TAP-Windows Adapter V9
Physical Address. . . . . . . . . : 00-FF-6A-2B-F0-FA
DHCP Enabled. . . . . . . . . . . : Yes
Autoconfiguration Enabled . . . . : Yes
Link-local IPv6 Address . . . . . : fe80::b404:5a8b:df0e:52c3%15(Preferred)
IPv4 Address. . . . . . . . . . . : 10.8.0.6(Preferred)
Subnet Mask . . . . . . . . . . . : 255.255.255.252
Lease Obtained. . . . . . . . . . : Sunday, July 30, 2023 4:25:02 PM
Lease Expires . . . . . . . . . . : Monday, July 29, 2024 4:25:02 PM
Default Gateway . . . . . . . . . :
DHCP Server . . . . . . . . . . . : 10.8.0.5
DHCPv6 IAID . . . . . . . . . . . : 335609706
DHCPv6 Client DUID. . . . . . . . : 00-01-00-01-2B-E4-62-78-08-00-27-43-77-E3

DNS Servers . . . . . . . . . . . : 172.20.1.2
172.20.1.7
NetBIOS over Tcpip. . . . . . . . : Enabled

Unknown adapter OpenVPN Wintun:

Media State . . . . . . . . . . . : Media disconnected
Connection-specific DNS Suffix . :
Description . . . . . . . . . . . : Wintun Userspace Tunnel
Physical Address. . . . . . . . . :
DHCP Enabled. . . . . . . . . . . : No
Autoconfiguration Enabled . . . . : Yes

Ethernet adapter Local Area Connection:

Connection-specific DNS Suffix . :
Description . . . . . . . . . . . : Intel(R) PRO/1000 MT Desktop Adapter
Physical Address. . . . . . . . . : 08-00-27-43-77-E3
DHCP Enabled. . . . . . . . . . . : No
Autoconfiguration Enabled . . . . : Yes
Link-local IPv6 Address . . . . . : fe80::6ca6:a423:e55d:a449%11(Preferred)
IPv4 Address. . . . . . . . . . . : 192.168.1.21(Preferred)
Subnet Mask . . . . . . . . . . . : 255.255.255.0
Default Gateway . . . . . . . . . : 192.168.1.20
DHCPv6 IAID . . . . . . . . . . . : 235405351
DHCPv6 Client DUID. . . . . . . . : 00-01-00-01-2B-E4-62-78-08-00-27-43-77-E3

DNS Servers . . . . . . . . . . . : fec0:0:0:ffff::1%1
fec0:0:0:ffff::2%1
fec0:0:0:ffff::3%1
NetBIOS over Tcpip. . . . . . . . : Enabled
...But, I can't ping the internal network:
Code:C:\>ping 172.20.1.18

Pinging 172.20.1.18 with 32 bytes of data:
Request timed out.
Request timed out.
Request timed out.
Request timed out.

Ping statistics for 172.20.1.18:
Packets: Sent = 4, Received = 0, Lost = 4 (100% loss),

C:\>What is the problem?

Thank you.
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