Linked by David Adams on Mon 21st Mar 2011 20:14 UTC, submitted by Anonymous
GNU, GPL, Open Source The GNU Project has announced a new project called GNU Free Call, an open source Skype alternative that will offer anonymous VoIP and will use the GNU SIP Witch server as the back end. GNU SIP Witch requires a minimum of system resources so it can be used on cell phones too so it seems the goal is to provide a cross-platform application, the immediate target most probably being Android.
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RE[3]: 'Twas about time
by Alfman on Tue 22nd Mar 2011 17:00 UTC in reply to "RE[2]: 'Twas about time"
Alfman
Member since:
2011-01-28

spidermain,

"The problem is not SIP, it's IPv4. IPv4 is obsolete since more than 20 years now. We just can't seem to get rid of it. We will have to deal with NAT and hacks around NAT until the end of time or until the Internet implodes."

Yes and No.

NAT is useful even if address space wasn't a problem. For example, I routinely forward SSH and SMTP connections using simple iptables forwarding. (Side Note: it is extremely disappointing that Linux IPv6 stack hasn't even implemented this port forward functionality).

Even if NAT is out of the picture, you ignored my point about SIP being impossible to firewall without custom code (an ALG). Presumably firewalls will have greater importance once (in the distant future) NAT gateways are gone.

There is no technical reason that SIP requires more than one (static) port, it is a design decision that will make SIP forever difficult to use.

Take note how relatively well P2P apps work behind NAT considering the limitations.


greygandalf,
"Everybody uses skype because it works, it passes through routers and works even inside big firewalled company networks."

Yep, AIX has that property too, but it hasn't seen much uptake, obviously due to the fact that it's incompatible.


"What would be needed is a skype-compatible implementation."

Skype has a tons of DRM in the protocol/client to make this impossible (when it's broken, they change it). They don't want to become a standard. This was a large reason most skype to telephone line converters need a computer, whereas SIP to telephone line converts are a standalone device.

"And, to complete the rant: The latest skype versions are really terrible, they have an indecent UI that looks like iPhone stuff brought to your workstation."

You're not the only one who thinks that: it sucks.

Reply Parent Score: 2

RE[4]: 'Twas about time
by spiderman on Tue 22nd Mar 2011 19:01 in reply to "RE[3]: 'Twas about time"
spiderman Member since:
2008-10-23


NAT is useful even if address space wasn't a problem. For example, I routinely forward SSH and SMTP connections using simple iptables forwarding. (Side Note: it is extremely disappointing that Linux IPv6 stack hasn't even implemented this port forward functionality).

don't agree. Even if you have a dedicated ssh server that has the same address as your router if that makes sense in your setup, voip clients should still have their own address as this is how they can be reached. NAT is pretty useless with ipv6. Just give one address per application if you need to.

Even if NAT is out of the picture, you ignored my point about SIP being impossible to firewall without custom code (an ALG). Presumably firewalls will have greater importance once (in the distant future) NAT gateways are gone.

There is no technical reason that SIP requires more than one (static) port, it is a design decision that will make SIP forever difficult to use.

Take note how relatively well P2P apps work behind NAT considering the limitations.

agreed, although this is not that much of a problem with ipv6 since your voip can have its own ip.

Reply Parent Score: 2

RE[5]: 'Twas about time
by Alfman on Wed 23rd Mar 2011 03:32 in reply to "RE[4]: 'Twas about time"
Alfman Member since:
2011-01-28

"don't agree. Even if you have a dedicated ssh server that has the same address as your router if that makes sense in your setup, voip clients should still have their own address as this is how they can be reached. NAT is pretty useless with ipv6. Just give one address per application if you need to."

Firstly, you still haven't addressed the firewall/ALG issue with SIP I brought up twice, which still exists without NAT.

Secondly, whether you choose to acknowledge it or not, port forwarding does have valid uses outside the scope of mitigating limited number IP addresses under IPv4.

One example is load distribution, the gateway router should have the ability to redirect inbound packets to multiple servers. This is an example of something NAT is good at.

Another example is the ability to use one domain name for multiple services. Domain names (typically) resolve to one IP address, without port forwarding/NAT, you're essentially forcing all daemons for one domain name to reside on a single server. This is a stupid limitation. For example, I may want 'domain.com' to have HTTP, FTP, SIP, all residing on separate servers. NAT/port forwarding on the gateway is far simpler, more efficient, and more scalable than forcing all protocols to be handled on one server.

Another example is a company moving servers to a new IP/location may want to port forward the requests on the old IP to the new servers' IP.

A similar example is when a server has maintenance downtime, the admin can forward requests at the gateway to an alternate server until the original server is ready. The port forwarding switch is instantaneous.

I definitely understand the motivation for IPv6 and eliminating the dependence on NAT. However, it seems you've overstated your case that it is never useful.

Reply Parent Score: 1