By using scp from your Desktop.
On the ASG move the wanted file to a location that is accesible for loginuser, e.g.
/home/login.
Then get a scp client software for your desktop e.g:
http://the.earth.li/~sgtatham/putty/latest/x86/pscp.exe
and run
$ pscp.exe loginuser@[Your ASG address]:http.pcap .