The quick answer is yes.

To make SendLink work from behind a firewall (or a router or proxy server that functions as a firewall), you need to do two things.

First, you need to specify the public (external) IP Address of your firewall in SendLink's Host Name Field. You can easily obtain this address from our Host Information page. In our experience, most Internet Service Providers configure their systems so that the IP Address and Host Name reported by that page are essentially equivalent. That means that there is no particular advantage to your using one or the other for the Host Name Field, since both will most likely change if your IP Address changes. If, on the other hand, you have a registered DNS Host Name that refers to your public IP Address, by all means use it since that will give you the most stable configuration over time.

Second, you need to access the port forwarding feature on your firewall. This feature is referred to as port mapping by some vendors. How you do this in specific detail depends on the firewall you are using, so check the documentation for the device or software you are using. In general terms, you need to allow an inbound TCP connection on the port number that is configured in SendLink's Port Field to the IP Address that is selected in the IP Address Field. Specify this same value for both the public (external) and the private (internal) ports. Make no assumption about what the firewall will do if either field is left blank. SendLink uses only one port for inbound connections. If the firewall configuration software allows you to specify a range of ports, use the same number for the lower and upper values.

The above two steps accomplish two things. The first step ensures that the links you send out refer back to the public access point of your LAN. The second step tells your firewall where to send those links on your internal network when they are used by remote users. The combination completes the loop back to your computer from the outside.

This is easily the most complicated aspect of using SendLink on the Internet. If you are in this situation and are having difficulty, please contact Technical Support. The more of these scenarios we hear about, the better we will be able to make our documentation and product.

As of version 1.6, SendLink supports the sharing of files which are up to 8 exabytes in size. Yes, exabytes. How big is an exabyte? Roughly a billion times a billion bytes!

SendLink's File Server is designed, top-to-bottom, for speed. That is not to say that we are not on the lookout for ways that we can make it even faster. But it does mean that we are not doing anything on purpose to get in the way of your computer sending files as fast as it possibly can to remote users. If files are not being sent as quickly as you expect, then it is reasonable to first look at that expectation to see if it calibrated properly to your setup.

One thing that many broadband users do not realize is that there is a difference — an asymmetry — between the rate at which they can download versus the rate at which they can upload. In fact, a 10-to-1 difference is fairly common, with the downstream speed being faster than the upstream speed. Check out the Speed Asymmetry sub-topic for a more detailed discussion of this.

For some ballpark performance numbers, and a discussion of the factors that influence those numbers, you might want to take a look at our File Server Performance topic. If SendLink is not matching your upstream capabilities as described in that topic, by all means give Technical Support a shout.

SendLink supports download resume. This support is always there in the SendLink File Server, it is just a question of which download software takes advantage of it. Download managers typically do, while Web browsers typically don't. If you are sharing particularly large files, your remote users should consider using a download manager that has a download resume feature.

Yes. Because files are sent directly from your PC to the remote user's, your PC needs to be on and connected to the Internet during the time you want to share files using SendLink in order to avoid creating broken_links. Naturally, SendLink must be running too.