I suggest you go (re?)read RFC 2385. Intuitively, it's called the TCP MD5 Signature Option, not the BGP MD5 Signature Option. Again, it's not insurmountable, though it is far, far better than nothing. -danny

BGP MD5 signatures do not protect the TCP/IP stream from spoofed TCP RSTs. The MD5 signature is checked at the BGP application layer after passing through and being acted on by the TCP stack. You can play all sorts of MAC, ARP, ICMP, IP and TCP games with the stream which MD5 won't prevent.