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Windows 10 default gateway, ignored

ericgandt

Junior Member
Sep 25, 2011
6
0
61
I have windows 10 installed, I have 2 NIC (well 2 active NIC with access to networks)
The first is 10.120.25.136 gateway 10.120.25.1 which is where I want to route all external traffic
the second is 10.120.27.136 which also has 10.120.25.1 as the gateway
So if I trace 10.120.25.62 it goes through 10.120.25.1 if I try for 10.120.23.22 it goes through 10.120.27.1 (wrongly).


Running route print shows:
IPv4 Route Table
===========================================================================
Active Routes:
Network Destination Netmask Gateway Interface Metric
0.0.0.0 0.0.0.0 10.120.25.1 10.120.25.136 25
0.0.0.0 0.0.0.0 10.120.25.1 10.120.27.136 15
10.120.25.0 255.255.255.0 On-link 10.120.25.136 281
10.120.25.136 255.255.255.255 On-link 10.120.25.136 281
10.120.25.255 255.255.255.255 On-link 10.120.25.136 281
10.120.27.0 255.255.255.0 On-link 10.120.27.136 271
10.120.27.136 255.255.255.255 On-link 10.120.27.136 271
10.120.27.255 255.255.255.255 On-link 10.120.27.136 271
127.0.0.0 255.0.0.0 On-link 127.0.0.1 331
127.0.0.1 255.255.255.255 On-link 127.0.0.1 331
127.255.255.255 255.255.255.255 On-link 127.0.0.1 331
224.0.0.0 240.0.0.0 On-link 127.0.0.1 331
224.0.0.0 240.0.0.0 On-link 10.120.25.136 281
224.0.0.0 240.0.0.0 On-link 10.120.27.136 271
255.255.255.255 255.255.255.255 On-link 127.0.0.1 331
255.255.255.255 255.255.255.255 On-link 10.120.25.136 281
255.255.255.255 255.255.255.255 On-link 10.120.27.136 271
===========================================================================

So both 10.120..25.1 and 10.120.27.1 are using 10.120.25.1 as the gateway, but running traceroute always goes through 10.120.27.1 which is not even listed, I am at a loss to explain why it is getting set. I also can not say why 10.120.27.136 has 10.120.25.1 set as a default, as it does not using the same dhcp on Linux.

On Linux I do not have this issue :
Kernel IP routing table
Destination Gateway Genmask Flags Metric Ref Use Iface
default 10.120.25.1 0.0.0.0 UG 100 0 0 enp4s0
10.120.25.0 * 255.255.255.0 U 100 0 0 enp4s0
10.120.27.0 * 255.255.255.0 U 0 0 0 bond0
link-local * 255.255.0.0 U 1000 0 0 enp4s0
172.16.80.0 * 255.255.255.0 U 0 0 0 vmnet1
172.16.95.0 * 255.255.255.0 U 0 0 0 vmnet8
192.168.122.0 * 255.255.255.0 U 0 0 0 virbr0

It is only Windows that is broken so it is not coming from DHCP, but something that windows is messing up!, basically .27 is 10Gbe Bounded internal backup and .25 is the external facing network, by sending data through .27 communication with other networks is broken.

Overall I have 4 networks 10.120.21.x (WIFI) 10.120.23.x (Internet of things), 10.120.25.x (main network) and 10.120.27.x (10Gbe LACP x2 backup and internal transfer). A Firewall controls all access between subnets as I'm security crazy.

Thanks,
ERIC
 

Railgun

Golden Member
Mar 27, 2010
1,289
2
81
It’s not being ignored, it has a better metric being on a “faster” interface as you can see in the route table.

Without knowing the rest of your setup, I can’t answer why that’s picking it up, but as a quick fix, I’d add a static default while you determine the source.
 

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