WAN with multiple static address; force LAN SUBNET traffic

RouterOS General
1

So I have 3 private subnets, 1 WAN subnet.

I want to force all web traffic from a specific subnet to exit via a specific outside/public IP in the WAN subnet. What’s the best way to accomplish this?

Thanks in advance

2

Here’s the routing setup other than the dynamic entries

/ip route
add check-gateway=arp comment="42 traffic" disabled=no distance=1 \
    dst-address=0.0.0.0/0 gateway=173.x.x.1 pref-src=173.x.x.42 \
    routing-mark=bits_traffic scope=30 target-scope=10

add check-gateway=arp comment="default route to rs" disabled=no distance=1 \
    dst-address=0.0.0.0/0 gateway=173.x.x.1 pref-src=173.x.x.41 \
    scope=30 target-scope=10

Here’s the firewall mangle entry

/ip firewall mangle
add action=mark-routing chain=prerouting comment="bits traffic" disabled=no \
    new-routing-mark=bits_traffic passthrough=yes src-address=10.1.1.0/24
3

try this:

add action=src-nat chain=srcnat comment="" disabled=no out-interface=WAN_INTERFACE src-address=YOUR_LAN_SUBNET to-addresses=YOUR PUBLIC_IP