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[#] Thu Mar 18 2010 14:14:17 EDT from cellofellow @ Uncensored

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Second part seems easy enough, not sure if I can do the first part. Stupid
router with a locked-down web interface. :(

Spell Binder's description of how it'd work seems well enough, if I could be
sure I have identical (or nearly so) configurations in both DHCP servers. Not
sure I can do that, will have to fiddle with the router.

On a different note, been doing some research and apparently running an i686
kernel on a VIA C3 is a bad idea, as the VIA doesn't support a certain
i686-only instruction (cmov, whatever that does). I tried to compile a C3-only
kernel yesterday, took all afternoon, and in the end I couldn't ping the thing
so had to reboot into the generic kernel. Then I tried to provision a couple of
EC2 VMs to speed up a new compile, but then I couldn't SSH into those, the
connection would die as soon as I'd logged in.

Ah, the joys of geekery.

[#] Thu Mar 18 2010 15:43:36 EDT from davew @ Uncensored

Subject: TCP windows in Linux

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I've been having problems with sending large files to my mail server and web server for some time now.

I couldn't quite define the circumstances for failures but I managed to do it today.

It has to do with the TCP window in the servers.

If the connections are just right like a fairly fast upload speed then the server keeps increasing the window size until its bigger than the router at the server end can handle and it all falls down.

I had to add

net.ipv4.tcp_window_scaling = 0

to /etc/sysctl.conf

and run sysctl -p

This prevents the TCP window growing dynamically and fixed my problems.

Thing is I'm not sure it was the best solution.

All transfer rates into and out of those servers now seem much faster and more stable but it just feels like the wrong thing to do somehow.

Anybody got anything to offer on this?

 



[#] Mon Mar 22 2010 00:29:08 EDT from IGnatius T Foobar @ Uncensored

Subject: Re: TCP windows in Linux

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Tuning TCP suitably for the underlying network is an advanced, but legitimate, activity.

[#] Tue Mar 23 2010 07:12:40 EDT from davew @ Uncensored

Subject: Re: TCP windows in Linux

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Well in my case its more like guess work.

I think I need a diagram explaining what each feature does.

 

Mon Mar 22 2010 00:29:08 EDT from IGnatius T Foobar @ Uncensored Subject: Re: TCP windows in Linux
Tuning TCP suitably for the underlying network is an advanced, but legitimate, activity.

 



[#] Tue Mar 23 2010 09:15:47 EDT from dothebart @ Uncensored

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maybe lartc.org could be helpfull?



[#] Thu Apr 01 2010 05:20:38 EDT from dothebart @ Uncensored

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Only when the last tree has died, the last river has been poisoned, the last fish has been caught, will we realize that we can't eat money.

oh. wrong context.

When the last class C subnet was assigned, the last class B is used men will see that its time to move to ipv6.

ICANN said, it ran out of ipv4 address space.



[#] Tue Apr 06 2010 00:27:04 EDT from the8088er @ Uncensored

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I've been messing with this for three days now and I haven't been able to figure it out.
My router is a PC with pfsense, which is a great FreeBSD based router package. I set up a PPTP VPN server on it for the purpose of, mainly, playing Starcraft with friends. Come to find out Starcraft uses UDP broadcast packets to find games which don't transfer over a VPN. I have been trying to set up an OpenVPN that uses TAP and what not and switches the networks instead of tunneling it or something like that and I just can't get the dang thing to work. I know that we VPN'ed Starcraft before but I believe it was between myself and two other people and all three of us had dd-wrt routers and the routers were switching the networks. It was also extremely unstable with the third person and adding a fourth killed it.
Now that I think about it though I think one of the clients was connecting with the VPN client built into Windows XP... so we had it working before!
If anyone knows how I can get this done please let me know! :)

[#] Tue Apr 06 2010 11:22:36 EDT from Spell Binder @ Uncensored

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When you say the game uses broadcast UDP packets, do you know if they're local-broadcast packets (dest IP=255.255.255.255) or subnet-directed broadcast packets (dest IP=192.168.0.255, e.g)? If they're subnet-directed, then they should be able to be routed just like any other IP packet. Otherwise, I agree that you'll need some kind of layer-2 bridging in order to get the packets across.

Have you investigated L2TP as a solution?

http://en.wikipedia.org/wiki/Layer_2_Tunneling_Protocol

I've not used it myself, but it will tunnel layer-2 packets, so it should work for your game. Plus, from the Wikipedia page, it looks like there's an implementation for FreeBSD.
L2TP Binder

[#] Wed Apr 07 2010 00:39:11 EDT from the8088er @ Uncensored

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I'm really not sure, but I think they're local broadcast because they're not working. :)

I did not originally go with L2TP because pfsense doesn't include it, but I upgraded to the 2.0 beta which does and enabled it. It doesn't work and it's a known issue, which will hopefully be resolved soon so I can let you know how it goes.

I could of course build my own FreeBSD router setup but I just like the ease of use of pfsense much better than having to figure out this stuff myself, but I may jump into it.

Routing tables scare me.

[#] Wed Apr 07 2010 18:04:15 EDT from Ford II @ Uncensored

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if you think routing tables are bad, check out iptables rules.

[#] Thu Apr 08 2010 21:10:51 EDT from IGnatius T Foobar @ Uncensored

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It all makes perfect sense to me, but then again, that's sort of "what I do"

[#] Fri Apr 09 2010 04:24:31 EDT from dothebart @ Uncensored

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port 22? isn't that what all those hackes use to do their evil? lets block that.



[#] Fri Apr 09 2010 10:50:35 EDT from Spell Binder @ Uncensored

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Nah! If you really want to be safe, you need to block ports 0 to 65,535.

[#] Mon Apr 12 2010 09:33:51 EDT from skpacman @ Uncensored

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Nah! If you really want to be safe, you need to block ports 0 to 65,535.


Then how will peoplez access my stuffs?? **research. research.**  :) remote servers are my friend.



[#] Mon Apr 12 2010 16:04:13 EDT from Spell Binder @ Uncensored

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Well, you could always roll your own transport-layer protocol on top of IP.
Then the only people who could access your site would be people you've given protocol implementations to. :P

[#] Tue Apr 13 2010 22:29:22 EDT from IGnatius T Foobar @ Uncensored

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Reinventing that particular wheel sounds like something that Ford would enjoy doing. Get to it.

[#] Thu Apr 15 2010 13:44:52 EDT from Ford II @ Uncensored

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Yes I would. Actually I did once. :-)
Actually I wrote I think I called it STUDP. or SPUDPyeah, that was it spud-p. stu protocol over udp.
the goal was to avoid the 3 way handshake on connections.
I got it to work and I got as far as writing something that could transfer files.
And I remember it beat FTP by 30something percent.
but I didn't have too much error recovery stuff so when udp dropped a packet, it rarely recovered.
Fun while it lasted.

[#] Sat Apr 17 2010 15:22:05 EDT from IGnatius T Foobar @ Uncensored

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Ironically, you were well on your way to developing a new P2P system.

You can do some really wild things with UDP.  The biggest deal with using UDP for a P2P system is that it's pretty easy to persuade everyone's firewalls to accept packets from each other on the UDP port which is bound to the application.  Skype/Kazaa do this quite well.  Multiplayer games are also pretty good at it (as I discovered when I performed "due diligence" with a sniffer while my kids played Mario Kart Wii in global multiplayer mode).



[#] Sun Apr 18 2010 11:24:01 EDT from Ford II @ Uncensored

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there's a lot of overhead with tcp that I think everybody just takes for granted and accepts, but when you NEED it to go fast, UDP works quite well.
I get the idea that UDP was the bastard stepchild of internet networking until popular systems like games and skype started relying on it.

[#] Sun Apr 18 2010 11:43:09 EDT from IGnatius T Foobar @ Uncensored

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I learned IP networking in 1992 at a router class in Massachussetts. The instructor compared TCP to Federal Express, who at the time had an advertising slogan indicating its use "when it absolutely, positively has to be there."

He then said that the U in UDP might as well stand for "Unreliable" because there is no guaranteed delivery. However, even then, it was used for some smaller applications, where if you didn't like the answer you got (or if you didn't get an answer) you could just ask again. This was often an advantage in the days when many networks either had very narrow bandwidth or had enough round-trip latency that you really didn't want to wait for a TCP handshake.

Now that we have big fast networks, UDP is experiencing a bit of a renaissance thanks to the need for peer to peer communications in a largely NAT-enabled world. Perhaps in the future if IPv6 kills off the widespread deployment of NAT, the pendulum will swing the other way.

If anyone is interested in reading about how UDP hole punching works, here are a few good articles on the subject (well, one good article and one Wikipedophilia article)

http://www.google.com/url?sa=t&source=web&ct=res&cd=1&ved=0CAYQFjAA&url=http%3A%2F%2Fwww.h-online.com%2Fsec urity%2Ffeatures%2FHow-Skype-Co-get-round-firewalls-747197.html&ei=1ifLS-11xYCUB-SRwIUG&usg=AFQjCNFwAdfxUR7 0tilI3BZTQbOSzLnLXQ

(sorry ... that should be http://tinyurl.com/y54ocpo )

and ... http://en.wikipedia.org/wiki/UDP_hole_punching


It's interesting enough that I'd like to try implementing it ... I just don't have any use for the finished product.

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