How to avoid icmp filter from known ip

[King C Shu <king@hashao.dhis.net>]

Hi

    My ISP keeps sending me this weird icmp message to verify
that I am online. Since I have rp_filter on(default in Debian?),
I always have this '10.128.50.254 sent an invalid ICMP error to a broadcast.'
warning displayed on my console. Since I know where does the
message comes from, I want to turn off the warning just for
this icmp message. How do I set it? 

Thanks.