[HELP] How to change sending interface

[ColinTaylor]

There is probably a lot of ip numbers for gmail

How about just using a fixed IP address in your sendmail command for the SMTP server rather than "smtp.gmail.com", e.g. 173.194.221.109. That way you can use your VPN director rule. OK, it's not a universal solution for everyone but it'll probably work for your purposes.

 

[Maverickcdn]

Not something Im familiar with at all myself either... if that wasn't apparent already

I guess Im just hung up on the fact the traffic is originating from the gateway (on the router), would he just leave the source IP blank in VPN director and specify the destination as 173.194.221.109? and does traffic originating on the router still hit the VPN director rules or does that only apply to clients (192.168.50.2-192.168.50.254) of the router?

 

[eibgrad]

Not something Im familiar with at all myself either... if that wasn't apparent already

I guess Im just hung up on the fact the traffic is originating from the gateway (on the router), would he just leave the source IP blank in VPN director and specify the destination as 173.194.221.109? and does traffic originating on the router still hit the VPN director rules or does that only apply to clients (192.168.50.2-192.168.50.254) of the router?

If the source IP is NOT specified, the rule will include ALL source IPs, including that of the router, on any and all of its network interfaces.

 

[Ranger802004]

I use x3mRouting addons to manage ipsets. It can create ipsets and get the host ip from dnsmasq. It also has the capability to route the ipset to WAN or any OpenVPN client.

GitHub - Xentrk/x3mRouting: Selectively route LAN clients, website or streaming media traffic over the WAN or OpenVPN client interfaces on Asuswrt-Merlin firmware

Selectively route LAN clients, website or streaming media traffic over the WAN or OpenVPN client interfaces on Asuswrt-Merlin firmware - Xentrk/x3mRouting

github.com

Initial reading of this document I’m not sure if I like the solution. Ipsets are beneficial for firewall rules but not routing, also I didn’t see any support for IPv6 (I have OpenVPN tunnel doing ipv6 for my needs and built a function for it. My current logic is that you can create routing policies and select from available VPN tunnel interfaces for that policy to route traffic and then from console add domains to that policy and then it will start building a database of queried IP addresses for the domain(s), kind of necessary since the router rebuilds the routing table after reboots and service restarts or specifically when OpenVPN interfaces are restarted. Current progress on the script is I have the install, uninstall, create policy, show policy, and add domain functions built and tested.

 

[octopus]

I have tested this and it's working. Have to figure out to change in vpn routing when it change.

SMTPSERVER="$(nslookup smtp.gmail.com | awk '(NR>2) && /^Address/ {print $3}' | awk '!/:/' )"

I can probably edit this for my needs.
https://charleswilkinson.co.uk/2021/11/21/asus-merlin-route-via-vpn-for-specific-destination-hosts/