thanks @Tom-Elliott

worked for me in the fog.deployimage option
like this
params
param mac0 ${net0/mac}
param arch ${arch}
set username myuser
set password mypassword
param username ${username}
param password ${password}
param qihost 1
isset ${net1/mac} && param mac1 ${net1/mac} || goto bootme
isset ${net2/mac} && param mac2 ${net2/mac} || goto bootme

The Problem with my previous approach was i tried do set this in one line
like

params
param mac0 ${net0/mac}
param arch ${arch}
param set username myuser
param set password mypassword
param qihost 1
isset ${net1/mac} && param mac1 ${net1/mac} || goto bootme
isset ${net2/mac} && param mac2 ${net2/mac} || goto bootme

make obviously no sense when i look at it now

Hello i tried the approch

original parameter file

login
params
param mac0 ${net0/mac}
param arch ${arch}
param username ${username}
param password ${password}
param qihost 1
isset ${net1/mac} && param mac1 ${net1/mac} || goto bootme
isset ${net2/mac} && param mac2 ${net2/mac} || goto bootme

now i changed this to
params
param mac0 ${net0/mac}
param arch ${arch}
param username myusername
param password mypassword
param qihost 1
isset ${net1/mac} && param mac1 ${net1/mac} || goto bootme
isset ${net2/mac} && param mac2 ${net2/mac} || goto bootme

when i select deploy image now i see all the avalieble images
but if i select on of those i got the a invalid login