SNAT local address going to a specific port

Braces and brackets are a bit misaligned. Try the following which should at least be syntactically correct:

when CLIENT_ACCEPTED {
    if { [IP::addr [IP::client_addr] equals "10.10.10.0/28"] && [UDP::local_port] equals "1700" } {
        snat "10.10.10.1"
    }
}