I have several ASA and same problem on all.
I want to use my tftp server outside my org, so i create a pat rule as usual, access-list and inspect on tftp is on. But i can't download any file, when i access it from the outside, i can see the request on the tftp server many times , but it doesn't start and goes on error communication. It works for other services (http / ftp)
I use this commands :
static (inside,outside) udp OutsideIPAddress 69 insideIpaddress 69 netmask 255.255.255.255
access-list 101 permit udp any any eq 69
access-group 101 in interface outside
Thanks for your answers.