@jknott said in OpenVPN tunnel network overlapping LAN network:
If they are in fact using /9 and not /8, then use the other half. Regardless, it's still best to use different addresses. What happens if the ISP decides to go with /8? I have done a lot of networking in business environments. I have learned there are commonly used subnets, which should be avoided to prevent collisions. That includes 10. and 192.168 subnets. So, I put my networks on 172.16 to avoid problems.
IMHO that's pure lottery
I have been using 172.16.x.x/12 ranges lots of times too.
The OP mentioned 10.0.0.0/9 , not me
I think i see something similar w. my ExpressVPN aka. they use RFC1918 for link addresses.
Here's a "snip" from a DEB10 VM , that is connected via them.
vpn-01:~$ sudo route Kernel IP routing table Destination Gateway Genmask Flags Metric Ref Use Iface ...SNIP... 0.0.0.0 10.141.0.35 128.0.0.0 UG 0 0 0 tun0 default 10.xxx.zzz.1 0.0.0.0 UG 0 0 0 ens192 10.141.0.1 10.141.0.35 255.255.255.255 UGH 0 0 0 tun0 10.141.0.35 0.0.0.0 255.255.255.255 UH 0 0 0 tun0 85.www.22.65 10.xxx.zzz.1 255.255.255.255 UGH 0 0 0 ens192 128.0.0.0 10.141.0.35 128.0.0.0 UG 0 0 0 tun0 ...SNIP... vpn-01:~$IMHO the OP could just as well use the high 10.x.x.x/9
Or take the chance with the existing network, until proven otherwise.
Btw: Neat trick with the 0.0.0.0/1