Use scp to copy the file to the PCs.
scp firewall <user>@<ip_address>:<path>
Then you just put the correct values in there and off you go. If this seems to manual you can write a shell script:
# list of all PCs in the LAN
IPS="192.168.1.1 192.168.1.2 192.168.1.3"
for ip in $IPS ; do
scp firewall <user>@$ip:<path>
The "problem" here is that you have to supply the password manually. FTP is another possibility.