I am attempting to set up an ipip tunnel from an SRX. The Internet interface is DHCP and the tunnel source is requiring an IP rather than an interface. My thought was to source the tunnel from a loopback interface. I used the "from zone junos-host" in a NAT rule and the SRX did NAT ping traffic when sourced from the loopback. However, the tunnel traffic was left un-NATed on egress. I also attempted to source the traffic from another routing instance but that did not change anything.
Does anyone have a working config for this?