Some material is very old and may be incorrect today
© June 2003 Tony Lawrence
How can I print to a remote PC that does not have a static IP
This is a fairly common problem: you have a PC at home and you
make some sort of connection over the internet to your server, but
your application needs to print to your PC. That would be easier if
your PC had a fixed, constant IP address, but your connection is
dynamic so it changes.
By the way: this article assumes a Unix/Linux server. It doesn't
talk about Windows apps, though often the solution is exactly the same
There are many, many ways to solve this problem. So many, in
fact. that I'll probably miss one or two in this write up. If I do
miss something, do let me know: it may help someone else down the
Some of these methods involve configuring an LPD printer on your
remote Windows machine. That's easy to do with Windows 2000 or XP
and Windows LPD clients are easily found for other versions. A
Google search for "Windows LPD Server" will turn up hundreds of
options, free and low cost. The concept here is that you define an
lpd printer on the server, and that its address will be looked up
by name.. somewhere. Some of these even help you do that
automatically, usually by way of something running on the server
that their software can contact. Some things you might want to look
at in this area include:
Other ways to do this are to use Windows SMB style printing.
That will require Visionfs, Samba or FacetWin on the server and
some help for those to "find" the connecting PC. Personally, I like
the LPD solutions better, but in some situations the SMB way can be
- Dynamic DNS services
Register a domain name and subscribe to a dynamic dns service. There are dozens of
them: Google search for "dynamic dns service" and pick what you
like. A little client runs on your Windows machine and updates the
service whenever your IP changes. When the server goes looking for
"xyz.com", the dynamic dns service tells it what your address is
This approach can work, though it also has its problems. The
issue, especially with the free and inexpensive services, is that
they may be slow or inaccurate in updating, which will kill you
dead for printing.
- Write your own DNS update client/server
This really isn't hard to do in Perl. The idea is to have a
little client on the Windows PC that probably runs at boot, figures
out its IP address, and contacts a matching server app on your
server to inform the system of your new address. Keep in mind that
thw Windows side doesn't need to try to figure out its address (and
may not even know it if it's going through a firewall); when it
contacts the server, the server will be able to tell where it came
from. You could even do this using a "port knocking" technique (see
What is "port knocking"?)
where you'd log the attempt to access some port and then scan the
logs to pick up the address.
See Dynamic DNS Services for examples
of writing your own update scripts.
- Use "local printing"
Local printing comes from old dumb terminals that, with the
proper escape codes, would then send all data received out another
port until a "stop local print" code was received. See http://aplawrence.com/Unixart/terminals.html
for more on that. Windows terminal emulators can often be set to
respond to the same codes and send the data to your Windows
Your application may make this a reasonable choice, or it may be
more difficult than you may like. Most terminal emulators (see
What are some terminal emulators I can use from windows? and http://www.anzio.com/support/whitepapers/printguide.htm)
- Use a VPN connection
Appliance VPN's are very inexpensive; for example see http://aplawrence.com/Reviews/rf550vpn.html.
Most of these can happily work with the remote side using DHCP, and
can also provide DHCP to the network (which may be only 1 machine
if remote). With a VPN, your address will (or can be) fixed as far
as the other side of the VPN is concerned: you are always
192.168.4.2 for example. See http://aplawrence.com/Basics/vpn.html
if you don't understand that yet.
- Manual methods
If you have root access to the machine you are using, just do a
"su" and edit /etc/hosts. You can get your address from "who -mux",
from netstat -a and all sorts of other ways: see How do I find out what IP address a user logged in from?
- Scripting it automatically.
Have something run from the user's .profile that finds out the
address and updates /etc/hosts (or DNS).
The problem here is that you need root access to update
/etc/hosts. There are three ways to solve that:
- You might use sudo: see http://aplawrence.com/Basics/sudo.html
or (OSR5) "asroot"
or (Unixware) "tfadmin and adminuser"
- Make a setuid binary that runs the script.
- Use a named pipe: the unprivileged client writes to the pipe, a
root owned process reads from it.
Some sample scripts for that are shown below.
# remotelpsetup, run at boot (run in background!)
/etc/fuser -k /dev/remoteprinters
/bin/rm -f /dev/remoteprinters
/etc/mknod /dev/remoteprinters p
exec < /dev/remoteprinters
# pickprinter, called from user's .profile
set `/bin/who -mxu`
MYALREADY=`grep $MYADD /etc/hosts| sed 's/ .*//'`
if [ "$MYALREADY" ]
test -z "$MYADD" && exit 0
case $MYTTY in
*) exit 0;
case $MYADD in
-) exit 0;;
192.168.*) exit 0;;
localhost) exit 0;;
*) : ;;
echo "Please select the printer you wish to use
case $choice in
[qQ]) exit 0;;
if test -z "$PRINTER"
echo "CookieM $PRINTER $MYADD" > /dev/remoteprinters
echo "Printer $PRINTER set for $MYADD"
read key printer address
case $key in
CookieM) : ;;
*) exit 0;;
/bin/grep -v $address /etc/hosts > /tmp/hosts.$$
/bin/grep -v $printer //tmp/hosts.$$ > /tmp/hosts2.$$
echo "$address\t$printer" >> /tmp/hosts2.$$
cp /tmp/hosts2.$$ /etc/hosts
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