0

I have an ISP box connected to a Netgear WiFi router.

Internet <-->[WAN] ISP box [LAN]<-->[WAN] Netgear router [LAN]<-------> Win7 laptop
                           192.168.0.x/24                192.168.1.x/24

I successfully configured both to enable IPv6 connectivity to Internet (with IPv6 next-hops configured in ISP box towards the WiFi router, whatever). Very happy, but I probably screwed a few IPv4 things in network layers of my Windows 7 laptop. I suspect that they are corelated, but I cannot find the spot :-(

IPv4 VPN

First, laptop connected via WiFi, Internet is accessible via IPv4 (192.168.1.x/24) and IPv6. I discovered that although I can connect to a distant private network via VPN (Forticlient, user/password accepted and connection established), no traffic is received; any ping -4 to the remote computers/routers fail:

C:\Windows\system32>ping 192.168.10.70

Pinging 192.168.10.70 with 32 bytes of data:
Request timed out.
Request timed out.
Reply from 192.168.0.254: Destination host unreachable.
Request timed out.

Ping statistics for 192.168.10.70:
    Packets: Sent = 4, Received = 1, Lost = 3 (75% loss),

Notice that 192.168.0.254 is my ISP box (gateway for WiFi router), there is no such IP on remote network (VPN), where these packets are expected to go!

C:\Windows\system32>ipconfig

Windows IP Configuration

Ethernet adapter Local Area Connection 9:

   Connection-specific DNS Suffix  . :
   Link-local IPv6 Address . . . . . : fe80::b8a8:bf09:275c:682c%31
   IPv4 Address. . . . . . . . . . . : 192.168.250.17
   Subnet Mask . . . . . . . . . . . : 255.255.255.255
   Default Gateway . . . . . . . . . :
[...]
Wireless LAN adapter Wireless Network Connection:

   Connection-specific DNS Suffix  . : lan
   IPv6 Address. . . . . . . . . . . : 2a01:xxxx:xxxx:xxxx:xxxx:xxxx:xxxx:xxxx
   IPv6 Address. . . . . . . . . . . : 2a01:xxxx:xxxx:xxxx:xxxx:xxxx:xxxx:xxxx
   IPv6 Address. . . . . . . . . . . : fd69:cdc6:cb9d::a6b
   IPv6 Address. . . . . . . . . . . : fd69:cdc6:cb9d:0:bcac:ce5b:6ae4:4caf
   Temporary IPv6 Address. . . . . . : 2a01:xxxx:xxxx:xxxx:xxxx:xxxx:xxxx:xxxx
   Temporary IPv6 Address. . . . . . : fd69:cdc6:cb9d:0:7d0a:715c:58db:8656
   Link-local IPv6 Address . . . . . : fe80::bcac:ce5b:6ae4:4caf%12
   IPv4 Address. . . . . . . . . . . : 192.168.1.239
   Subnet Mask . . . . . . . . . . . : 255.255.255.0
   Default Gateway . . . . . . . . . : fe80::xxxx:xxff:fexx:xxxx%12
                                       192.168.1.1

The routing table seems normal:

C:\Windows\system32>route print -4
===========================================================================
Interface List
 31...00 09 0f aa 00 01 ......Fortinet SSL VPN Virtual Ethernet Adapter
 30...00 09 0f fe 00 01 ......Fortinet virtual adapter
 24...xx xx xx xx xx xx ......Intel(R) Ethernet Connection I218-LM #3
 16...xx xx xx xx xx xx ......Microsoft Virtual WiFi Miniport Adapter #2
 14...xx xx xx xx xx xx ......Bluetooth Device (Personal Area Network)
 12...xx xx xx xx xx xx ......Intel(R) Dual Band Wireless-AC 7260
  1...........................Software Loopback Interface 1
===========================================================================

IPv4 Route Table
===========================================================================
Active Routes:
Network Destination        Netmask          Gateway       Interface  Metric
          0.0.0.0          0.0.0.0      192.168.1.1    192.168.1.239     10 << Default route
        127.0.0.0        255.0.0.0         On-link         127.0.0.1    306
        127.0.0.1  255.255.255.255         On-link         127.0.0.1    306
  127.255.255.255  255.255.255.255         On-link         127.0.0.1    306
          a.b.c.d  255.255.255.255      192.168.1.1    192.168.1.239     10 << VPN server @ a.b.c.d
      192.168.1.0    255.255.255.0         On-link     192.168.1.239    266
      192.168.1.1  255.255.255.255         On-link     192.168.1.239     10 << WiFi router
    192.168.1.239  255.255.255.255         On-link     192.168.1.239    266 << WiFi address
    192.168.1.255  255.255.255.255         On-link     192.168.1.239    266
     192.168.10.0    255.255.255.0   192.168.250.18   192.168.250.17      1 << Remote net
     192.168.14.0    255.255.255.0   192.168.250.18   192.168.250.17      1 << Remote net
   192.168.250.17  255.255.255.255         On-link    192.168.250.17    257 << VPN connection
        224.0.0.0        240.0.0.0         On-link         127.0.0.1    306
        224.0.0.0        240.0.0.0         On-link     192.168.1.239    266
        224.0.0.0        240.0.0.0         On-link    192.168.250.17    257
  255.255.255.255  255.255.255.255         On-link         127.0.0.1    306
  255.255.255.255  255.255.255.255         On-link     192.168.1.239    266
  255.255.255.255  255.255.255.255         On-link    192.168.250.17    257
===========================================================================
Persistent Routes:
  None

Wired connection

I then noticed that when I disable the laptop WiFi and connect an Ethernet cable between the laptop and the LAN switch of either the router or the ISP box, the laptop fails at getting an IPv4 address (stays on APIPA 169.254.x.x).

According to Wireshark, it seems to send a DHCP request repeatedly but no answer is received. Traffic from other devices of the LAN is well seen on Wireshark trace.

I tried ipconfig /release then /renew with no more success. May it be necessary to use more intrusive methods to reset IPv4 stack to a cleaner state?

Comparison with another laptop

I tried all those tests on another Win7 laptop: it encountered no such issues at all.

  • VPN connection is OK, ping 192.168.10.70 is successful.
  • The routing table is similar (with some different IP addresses, as expected).
  • Wired connection obtains an IP address with no delay.

All of that is strongly supposing that the issue is really located on the first laptop (and not router stuff). But now I need your help to investigate further...

0

The two issues were unrelated.

For the wired connection: the autonegociation set up a 1Gb link which was not compliant with the hardware in use. The laptop was able to read incoming traffic (all?), but all outgoing traffic was not understood by routers that I tried to connect. Forcing interface to select 100Mb bandwidth fixed that issue.

For the VPN access, seems like Wireshark + npcap were causing trouble with VPN tunneling, since after uninstalling them, VPN is now fine.

| improve this answer | |

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

Not the answer you're looking for? Browse other questions tagged or ask your own question.