Some people are grateful for what you give them; others just want more. This is a networking/internet question, for those who might care to help me solve this problem:

The IM Image/Talk/File Transfer (things that require a direct connection?) features of AOL Instant Messenger no longer function for the computers sharing my DSL at home. In fact, they never functioned for any computer sitting behind this router (Linksys BEFSR41, non-wireless). These features work fine on analog modem or even through the DSL modem if it's directly connected to a computer. Anyone have any idea why? And can this be remedied, so that my sister will stop bitching at me about being able to send pictures to people that don't care?

I think you need to open up ports 4443 and 5190. One is for direct connection, the other for file xfer, I think. Go into the router's config menu and go to Advanced, then Forwarding, and add entries for those ports to forward to your PC.

Also check this out, apparently AIM made some software changes to make it easier to work from behind firewalls. Haven't used it, since I use Trillian, but it might help you out.

Your firewall/NAT/router thing takes the one IP address given to you by your ISP and distributes it amongst the computers at your house. It does this by taking that IP address for itself and handing out totally different addresses to your computers that the internet at large doesn't know about. When those computers try to make a connection to the internet, it rewrites the envelopes of the data so that the internet sees that data coming from the ISP address so that the computers on the other end know where to send a response back to. The firewall thing then sees the response and can associate it with the computer that sent out the original request and rewrite the envelope so that it gets it.

Where this breaks down is when a computer on the internet wants to send data directly to one of your computers. There's no association to be made for the firewall to know where to send the data, so it just drops it. This is part of its firewall-ness. You can configure it so that it knows that certain types of data go to a specific computer, but this fails when you don't know which computer that's going to be.

AOL's ancillary AIM protocols work a little backwards. Your computer sends a message to the remote system to tell it to start up a new connection back to your computer. When it does so, the firewall sees a new connection, but has no way to associate that with the original AIM communication, doesn't know what to do with it, and drops it on the floor.

It would be possible for a firewall to inspect AIM communications so that it could make an association for the incoming communication, but I don't know of any that actually do this. The other option is to configure your firewall to forward all such incoming transmissions to go to a specific computer, but that means that that sort of communication will go only to that computer. In other words, if you wanted to do an AIM file transfer, you have to be on that computer.

This explanation avoids a lot of the technicals, but I think that it's not inaccurate, just imprecise.

The internal firewall of your router is causing this by blocking the ports that IM uses.
You should open up these ports in the firewall configuration model of the router. To know which ports you need to open, check this list.


I used to use MSN and found out that it practically required me to open all my ports if I wanted it to work right. (especially if I wanted to use video conferencing).

In the end I just ended up putting one of my PC's in the DMZ and putting Zonealarm on it to still give it some form of protection.

You'll find that even opening up the ports as sugested won't fix the problem. AIM is backwards enough that it sends its IP address to the server in the data of the packet. Thus, you have to rewrite the packet to actually get it to work. It is rumored that the new version is better, but I havn't tried it out.

One thing that came up on the BBS recently is Reaim, avaible here: http://reaim.sourceforge.net/ but it's going to require a linux box on the outside, and some knowledge of what needs to be set up.

Matthew

... but it's going to require a linux box on the outside...

Well that's not a likely solution. Anyhoo, I've done some general research on the web and have found many forums where people have asked just this question. It basically comes down to this: AIM is not NAT friendly. There is a beta version currently out which supposedly solves this problem (linked earlier in this thread), but there are no guarantees.

So basically, anyone who wants to use AIM features like Talk, IM Images, or File Transfer and is behind a Linksys or similar router simply has to wait. Assuming, of course, that the current beta version doesn't do the job for them. My sister is unwilling to run a beta version of any software. So she waits.

Thanks for the help, guys.

My sister is unwilling to run a beta version of any software.

Yet she runs Windows. Hmmmm.

She's not very computer literate. She just didn't like the idea of "beta" when I explained it to her. She'd rather I test it out and let her know if it works.

She just doesn't realize that ALL microsoft software is beta until it is discontinued, then it becomes obsolete.

i thought i read somethin about a new firmware revision that solved this exact problem.

Again, I've found several threads on several boards on this subject, through my searching. The problem lies with AIM, not the router. Or so all of these threads conclude. And there is a beta version of AIM out that supposedly solves this problem, which I haven't had time to test yet.

I have the latest firmware for my router. And its release notes do refer to better compatibility with AOL, which would let one hope that would transfer to AIM. But I didn't really expect it would.

I will test that beta version of AIM soon and post my results.

The problem lies with AIM, not the router.

BTW, sorry about my misinformation above. I made an assumption without testing (despite the fact that I thought I'd solved this problem before in that manner -- must have been something else).

Yeah, I same the same problem as well. It's a problem with how AIM works, not with anything else. Hopefully the new version will fix this problem.

Well, you were actually pretty close as regards 'why' this is an issue, although active ftp is closer to what you were describing. The effect of NAT on this type of comms is pretty much the same. You can rewrite the packets if your firewall lets you use inspect script like FW1 or similar. It then only becomes a real pain if your packets are encrypted (IPSec - Akkkkkk!!)

you were actually pretty close

It's not that I don't understand the issues; I just made an assumption about how AIM file transfer works that was, apparently, unfounded. (Well, it was founded in that I thought I'd solved this before and that even AOL engineers couldn't be that stupid. I guess I was wrong on both counts.)

I will test that beta version of AIM soon and post my results.

It works. All that frustration solved by a simple upgrade. My sister will be ecstatic. For those interested, the version number of the AIM beta is 5.2.3139. No special settings were required on my router or elsewhere.

/me gets excited in hopes that Trillian may soon be able to use that upgraded protocol.