Use the packet dispatch table to handle USERAUTH_BANNER messages, which should
[u/mdw/putty] / testdata /
drwxr-xr-x   ..
-rw-r--r-- 5064 colours.txt
-rw-r--r-- 112 lattrs.txt
-rw-r--r-- 468 scocols.txt
-rw-r--r-- 1757 utf8.txt
-rw-r--r-- 737 vt100.txt