[Koodari]

I have an iBook connected to a cable modem via Ethernet. Then I have a Firewire cable connecting it to another iBook. Settings seem to be okay - iBook #1 gets its settings via DHCP from the cable modem, and iBook #2 gets its settings via DHCP from iBook #1. Internet sharing is enabled. I dropped firewalls on both computers just to be sure they are not causing any trouble. There are no proxies or special settings in use that I know of. I gave iBook #1:s Firewire interface a manual IP of 192.168.2.1, which it seems to default to anyway.

The problem. I can do filesharing between the iBooks, I can reach other computers on the Internet from iBook #2 using ping and ssh, but Safari or Firefox on iBook #2 will not give me a single page! iBook #1 is working fine. Any idea why this could happen? Cable company says they have not changed settings, but I don't exactly trust or like them.

I think the same setup, but substituting iBook #2 with a Powerbook, has worked before without problems.

[sildani]

As a step for troubleshooting, try accessing the web using IP instead of a name. For example, http://216.109.118.76 should take you to yahoo.com, at least at the time of this posting. If it works, then you've isolated the problem to being a DNS issue. I don't remember off the bat if you can set IP by DHCP and DNS manually, but if you can, then copy iBook #1's settings for DNS alone into iBook #2. That should work. Or, try setting iBook #1 as the DNS server, although I don't think that would work without running some DNS server daemon on iBook #1.

Let me know if any of this helps.

[Koodari]

I tried DNS already by pinging hosts by DNS name - I picked hosts that are guaranteed not to be in any cache on iBook #2. DNS works. There are no manual DNS settings, all come in by DHCP.

[sildani]

That's a good thing, that you can resolve names. I think the next part you should focus on is the software. Try a different browser (Firefox, IE) and see if it works, or check out the settings on Safari. I don't have my powerbook with me at the moment so I can't help much more. If I get the chance, I'll log on tonight and see if can offer any more help.

Nonetheless, if you can ping by DNS, that's a very good sign. You are pretty close to getting it to work.

[Koodari]

Already tried the different browsers before posting the thread.

Just now the Firewire connection started acting up and not getting established after the cable is attached. I did permissions repair on both iBooks now. I am going to shut them down, try again tomorrow. I could switch iBook #1 with iBook #2 in this setup. I also think I should try telnetting out to various ports like the http port and see what I get.

[sildani]

Have you considered buying a broadband router w/ switch? The 4-port Linksys variety can be found pretty cheap on eBay, other brands even cheaper. The router can also act as a hardware firewall, you can set up logging to monitor access to your network. It may be easier to do just that.

[Koodari]

I booted up the iBooks again after permissions repair and now they work. It's nice they do, but I'd much prefer it if I could locate and fix problems without resorting to generic "fix-all" procedures. I got enough of that, especially the reboot band-aid, on Windows.

[sildani]

Originally Posted by Koodari I got enough of that, especially the reboot band-aid, on Windows.

I hear ya, one of the reasons I switched myself.

Remember that under the skin OS X is an implementation of FreeBSD. So perhaps there were some other things to look into (iptables perhaps?) to figure out the percise problem. While I don't miss the "band-aid" fix-all type solutions, I am glad they are there, and that they work.

If you ever do find out what caused it, please post it here.

[thuh Freak]

iptables, iirc, is a Linux kernel thing, so very unrelated to FreeBSD and quite disconnected from Mac OS X.

i would have been curious as to what telneting to web servers on port 80 would have produced. From there, you could manually act as a http client ("GET /<enter><enter>" should return the headers and html for the server's root index page). If that worked, and a browser couldn't get to that same page, then it'd definitely be a browser issue.

but, well, since its fixed, seemingly from the permissions repair, it'll be hard to ever track down what caused the problem.

[sildani]

Originally Posted by thuh Freak iptables, iirc, is a Linux kernel thing, so very unrelated to FreeBSD and quite disconnected from Mac OS X.

I stand corrected... I am not familiar with FreeBSD per se, although I've worked on Linux, and usually work out issues like these by looking to the iptables or ipchain configuration.

[Koodari]

I could somewhat replicate the problem.

I connected the iBooks again (only #1 says put, I take #2 elsewhere occasionally) and the iBooks would not connect via Firewire at all. I tried asking for a new DHCP lease, no result. I tried yanking the cable and restoring it, no result. Finally restarting the sharing service and yanking the cable yet again gave a connection, ping and ssh. I observed the old behavior of web inavailability. Then telnetted to www.amazon.com:80, which gave me a connection but disconnected me after I put in the first command. Tried that again. Then tried another server, www.yle.fi:80. Got the page. Then tried a browser again (which was open this whole time) and it worked, on both addresses. For general interest I tried telnetting to Amazon again and observed they still disconnect the telnet client even though with Firefox I get the page.

I'm pretty sure that yesterday, time did not fix the problem.

Any ideas what might be going on, or further diagnostics? I expect these problems will occur again.

[thuh Freak]

the fact that the dhcp lease was flaky may be a clue. still not sure exactly what the answer is though. if i remember my networking 101 class, the first thing we should always check is the lowest layer: the wire. If you have an extra firewire sitting around somewhere, try using that and see if everything is still flaky. Failing that, network class told me we're supposed to go up and up each layer until we get to application layer; but fuck that. if it aint the wire, its probably something high-up. I'm inclined to think that the sharing service on #1 is broken, or inhibited, in some way. Possibly, normal use of the computer (or maybe a program like Limewire? i'm guessing really) is flooding your internet connection, and therefore #1 cant serve #2 quick enough resulting in timeouts. this could account for the on-again off-again service (since limewire/similar-programs are only heavy on the network during a search and a transfer; and aren't consistently heavy). I know that when my gateway computer (ie, my #1) has limewire open (for research purposes of course ), all my other computers struggle to do anything on the internet.

[sildani]

Still wondering why Koodari doesn't just get a broadband router...

[Koodari]

Originally Posted by sildani Still wondering why Koodari doesn't just get a broadband router...

Because they are way, way overkill for this job. I just need to get internet access shared for a few days, couple times a year, when I'm at my parents' place. iBook #2 is mine and #1 is theirs.

Besides, I hate unnecessary complexity. If I can do a job with simple commands in the OS, I prefer that to a utility app. If I can do a job with a firewire cable, I prefer that to a router. I always seem to lose time when I try to cut corners and switch to a more complex solution instead of figuring out why what I have does not work. And it's not just a question of time. If I push a problem behind me, cross my fingers and hope "black magic" keeps things working, it undermines my confidence both in myself and the computer.

It seems like even if the network settings GUI, ifconfig, ipconfig and such show that the network works, it doesn't work immediately. First I can ping the other iBook, later I can ping out, later still I can telnet or browse to the same server.

I need to re-test things to see if there really is such a weird "activation sequence" or if that was a misperception. Is there anything that could cause a browser to delay upon the network changing? Or anything that could cause ICMP and HTTP ports to become available sequentially, not simultaneously, through the routing iBook?

I'd test the firewire cable, but I don't have an extra available and I don't think there can be anything wrong with it since the connection eventually starts working.

[FFL]

I gave iBook #1:s Firewire interface a manual IP of 192.168.2.1, which it seems to default to anyway.

That might be a problem - maybe leave it as automatic instead of manual??

Otherwise, I'd try AirPort instead of FireWire, unless the iBooks don't have cards because they are older models from before the cards were pre-installed

[sildani]

Originally Posted by Koodari Because they are way, way overkill for this job. I just need to get internet access shared for a few days, couple times a year, when I'm at my parents' place. iBook #2 is mine and #1 is theirs ... Besides, I hate unnecessary complexity. If I can do a job with simple commands in the OS, I prefer that to a utility app ...

You can't argue with results, right? The non-wireless 10/100 broadband routers are cheap enough to make their cost a non-factor, and they are really simple to configure (you'd be up and running by now).

However, if this is a learning exercise as well, then of course by all means you should get down to the bottom of the problem, and figure out how to solve it. IMHO, we have many levels of indirection for a reason, and after years and years of experience with this stuff, we should learn from our techy forefathers.

I look forward to seeing future responses in this thread and what conclusions you come to. Good luck, and sorry I couldn't be of much more help

[thuh Freak]

Originally Posted by Koodari Is there anything that could cause a browser to delay upon the network changing? Or anything that could cause ICMP and HTTP ports to become available sequentially, not simultaneously, through the routing iBook? I'd test the firewire cable, but I don't have an extra available and I don't think there can be anything wrong with it since the connection eventually starts working.

its been my experience with GUI browsers that underlying network changes (like dhcp release/renew, or manual ip change, or anything low-level) means i have to re-start the browser to get internet working again. but i have never really dug into the code of any browser, so that might just be one or two badly coded browsers that i've encountered.

on the ICMP/HTTP sequentiality thing: No. First, ICMP doesn't run on TCP, IIRC (acronym trifecta in one sentence; lets see how many more i can get in this paragraph). ICMP, methinks, runs in connection-less mode (ie, datagrams, UDP, other synonyms, ...). I cant think of why one would depend on the other. Well, its possible (and extremely unlikely) that the hypertext transfer protocol utilizes ICMP during page downloads, or maybe the client tries it before submitting a request. I haven't looked through the RFC for HTTP in a long long time, but i dont remember anything like that. it would be kind of dumb to do that, if http does it.

Either ICMP or HTTP can be blocked by a firewall (I know you said u turned ur firewalls off), and of course can be blocked independantly of eachother. BUT, i cna't think of a reasonable reason for an ISP to block either (they are both of huge value for home users). so i doubt its a firewall issue.

It would be interesting to know what your gateway/router ip is on the #2 box. is it 192.168.2.1? what is it when things aren't working? i think FFL is right, we should just the automatic settings that box #1 gets, and let it propogate based on that.