Is "TTL hard to spoof" useful?


Well, since the vast majority of (eBGP) our peerings are between adjacent routers 

So why not set the TTL on BGP packets to 255 and then reject any BGP packets that come from configured peers which do NOT have a TTL in the range 255-254?

That is, the receive TTL is expected to be within a small range of 1 or 2 (254-255). The actual value depends upon the (router) architecture, but it is expected that the receiver will verify the range