Port Forwarding

[jjocsak]

I've seen many references to "port forwarding" in these forums.

What exactly is this?

Why use it?

Are there instructions somewhere detailing how to do it?

Thanks
Jeff

[voip123]

I've seen many references to "port forwarding" in these forums.

What exactly is this?

Why use it?

Are there instructions somewhere detailing how to do it?

Thanks
Jeff

You don't need to have any port forwarding at all.

[caseydoug]

I'm not sure I would say you don't need any port forwarding at all. Port forwarding is used when your VoIP adapter is behind a router and calls are having difficulty navigating their way through your network to reach the adapter. You router allows you to direct packets aimed at a particular port on your public ip address to the private ip address of a device behind the router. So, for example, a packet aimed at 24.213.102.11:5060 (port 5060 of your public ip address) can be forwarded to 192.168.100.25:5060 (port 5060 of your VoiP adapter's private ip address).

If you are having problems (one-way audio, dropped calls, no ringing, etc.), contact support and they will tell you which ports to forward and help you do it.

[usa2k]

I agree with the purpose of port forwarding.

If your ATA works directly connected to the modem, and not behind a router, I would question your network, or the quality of the router. Port forwarding in that case can be a bandaid to overcome your network issues.

People may sometimes forward Port 80 to an internal web server. This allows a web server to be reachable from an otherwise unreachable NAT address. These are techniques to overcome the normal rules of the router.

In SPI firewalling, the ATA will send a packet on a regular interval to the VoIP provider. The SPI firewall blocks all uninitiated communication to the router. Same as when your browser requests network data, there is a short interval where replies can come back via the outbound info sent. The response must be quick enough or the whole deal is over and the SPI firewall opening is again closed. The registration interval of an ATA must be compatible with the window of opportunity the SPI firewall allows.

No dial tone for example, can be the effect of loss of this registration. Poor ISP connectivity can also muddy this scenario. Port forwarding allows a limited way in to the ATA to establish communications. Beyond the Port 5060 port being forwarded, I would hazard a guess that the network traversal by the modem is doing a poor job. I would seriously think about replacing the router if it works fine directly connected to the modem.

It would be an interesting statistic, to learn about what modem combinations need port forwarding, and if more than the key port needs to be forwarded.

[burris]

I too, am from the no port forwarding school in order to make the basics work.

If what you all say is true, then we would all have to use DMZ and forwarding, etc.
I don't choose to use the ATA or my DSL modem, for that matter, to do any other functions than I believe it to be designed to do. I have a router for PPPoE as well as routing for my VOIP ATA.
I think that when these isolated problems occur, they are as a result of mis-management on the users setup, and these work-arounds should only be necessary in rare cases when a diagnosis is not available or perhaps when there are esoteric setups that fall outside the realm of provider supplied and provisioned ATAs. This may even extend to unique arrangements with the users ISPs as well.
Just my opinion...

[chpalmer]

It would be an interesting statistic, to learn about what modem combinations need port forwarding, and if more than the key port needs to be forwarded.

Good idea usa2k- Ive just started a post with mine...


http://forums.voipo.com/showthread.p...4664#post14664


I have multiple systems at the office and of coarse Voipo here. Im constantly moving and testing things and never need any port forwarding. But I believe that some manufacturers just don't have enough knowledge to properly handle voip through their devices.

My firewall does not like to allow incoming calls unless they originate from the carriers port 5060 (or whatever my device is pointing at) so I simply give the carrier server a firewall rule to allow all ports and problem solved.

[caseydoug]

Sometimes port forwarding is needed no matter how well designed your network and equipment are. For example, I have three and sometimes four VoIP adapters operating behind my router (plus soft phones), and some of them are reached directly -- i.e., without using proxies. There would be no way a call could reach myadapter@mypublicipaddressort without forwarding that particular port to my adapter.

Edit: the smiley should be a colon and a "p."

[chpalmer]

I have three and sometimes four VoIP adapters operating behind my router (plus soft phones), and some of them are reached directly -- i.e., without using proxies.

Are you saying the provider system refuses to recognize NAT? Or that your ATA is unable to be set to recognize its behind NAT??

I know on one of my ATA's, I believe its A Grandstream, that one setting can influence that behavior at the carrier side...

[scott2020]

My firewall does not like to allow incoming calls unless they originate from the carriers port 5060 (or whatever my device is pointing at) so I simply give the carrier server a firewall rule to allow all ports and problem solved.

I had a voice gateway I left 5060 open to pretty much every connection. That was a mistake! Basically someone could enter phonenumber@my ip address and the call would go through. Not good! I have since locked it down so don't go getting any ideas!

[chpalmer]

I had a voice gateway I left 5060 open to pretty much every connection. That was a mistake! Basically someone could enter phonenumber@my ip address and the call would go through. Not good! I have since locked it down so don't go getting any ideas!

Your running a sip server?

My rule is setup as-

174.37.45.134 - UDP - all ports > lan address all ports (I do this for each of Voipo's servers.)

So unless sip-*.voipwelcome.com gets hacked or someone spoofs one of their addresses, ect... I should be safe...