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Servers internet access keeps going down


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mikeaman's Avatar
mikeaman mikeaman is offline
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24-Apr-2007, 01:19 PM #1
Servers internet access keeps going down
Hi all,

I have an issue that I am hoping someone might know how I can resolve it. First let me explain our setup.

We have 3 servers all running MS Server 2003. One of them is our Mail (exchange), print, and net server (our main server). The other 2 are file servers. We have about 25 computers that access the servers, and to get to the net they access access our main server (call it server 1), which has the cable modem connected to it.

OK, so here is the deal. About 3-5 times a week the internet goes down on the server. Everyone can still access the servers via the LAN, but cant get out. Odd thing is that 90% of the time it goes down at night (when no one is accessing it, at least not here).

What I have to do is a couple of things. I either have to:

1) Unplug the cable modem and plug it back it
2) Go into the server and disable then re-enable the network card.
3) Restart the server.

Most of the times I have to do #1 or #2. When its #1 I cannot even ping the modem, in which case I know something is up with just the modem. When its #2 I can ping the modem, but cant access the net. Sometimes I have to do both #1 and #2.

This server (server 1) has 2 gb of ram and is a 1 ghz machine, with plenty of hard drive space left.

I guess what I would like to know is what your guys opinions are. Is it something with the server, or just the modem? Needless to say my boss is getting rather annoyed with this and is willing to purchase a new server if thats what it is.
pinntech's Avatar
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24-Apr-2007, 09:37 PM #2
Are you saying that your server is directly hooked to the cable modem?

If your server is directly hooked to your cable modem and you cannot contact it, it is definitely your cable modem or ISP's connection.

I think it would be highly unlikely that you would have the cable modem hooked directly to the server. Do you have a router or switch between the cable modem and servers/workstations?

Care to explain your network setup a little further? Then I can make some suggestions on how to troubleshoot the issue.
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mikeaman mikeaman is offline
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25-Apr-2007, 11:29 AM #3
Yes the modem is plugged directly to the server. The modem its-self has a built in router. In any case the reason I tend to think its not the cable modem/router is due to the fact that I can ping the modem its-self when the net goes down, and I get a reply back (and I have been pinging it from home to test). But when I come in to work and log onto my computer (or the server, or any other computer on the network), I cant get to the net.

BTW it happened again today. Thats three days in a row. This time I was once again able to ping the server from home, so when I got to work what I had to do was go into network connections, and disable then re-enable the NIC. That once again solved the problem.

Its just odd to me that it decides to die every night. Is there anyway to tell on the server when the net went down (exact time)? I suppose I could write a little script that pings the server every few min to determine when it goes down.

Here is my guesses on what the problem is (a few dont seem very likely though)

1) Router/Modem (though like I said we just got a new one a few months back)
2) The NIC card on the server (doesnt seem like this would be it though)
3) DOS attack

3 days in a row all happening in the early morning (I know its after 2 am, but exactly when I am not 100%, but will find out the next time).

Thoughts?
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mikeaman mikeaman is offline
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26-Apr-2007, 11:42 AM #4
Well the server did not go down today... Here is another thought. We do network 3D renders at night. Do you think that could cause this? I will be asking my graphic designer to determine if we indeed did one monday and tuesday, but not yesterday. That may be what it is.
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26-Apr-2007, 07:32 PM #5
Sorry, I didn’t get a chance to reply yesterday!

So, do you have any control over your cable modem with built-in router? Can access the configuration of it? Does it have a firewall and/or logs in it?

Do any of your other computers connect to the cable modem’s router?

The reason I am asking is because “routers” do freeze up in strange ways. I had one that would freeze up all of the time on the WAN side. All of my internal systems running off of this router could communicate, but they could not access the internet! I had to either unplug the router or use the router’s built-in “release” and “renew” buttons. Once again, everything internal could communicate!

I really, really need a good description of how your network is setup before I can really provide suggestions. Can you give me a general run down on how your network is setup? As in the paths they take to access the internet and so forth? Are there other switches or firewalls in place? If so, what types? Also, what type of internal IPs are you using? Dynamic or Static? If they are dynamic what servers as the DHCP server?

I don’t think it will be your renders causing it! It’s not impossible, but I highly doubt it is the problem.

I need to know the answers to the above questions before I can make any suggestions. If you don’t have anything else on the cable modem’s router, you might want to hook a laptop or PC to it and see if it can still access the net the next time the server freezes up.

Okay, let me know about your network and then I’ll have some suggestions.

Thanks!
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Daredeval756 Daredeval756 is offline
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26-Apr-2007, 07:37 PM #6
i too had this issue, i got cFOS Traffic Shaper and it fixed the problem....
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29-Apr-2007, 04:31 PM #7
I don't think CFOS would help him much here. I am still waiting to see his network setup, but I'm still tipping on his cable modem with built in router as being the problem.
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Daredeval756 Daredeval756 is offline
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29-Apr-2007, 04:36 PM #8
yes probably, but my connection bombed out for the first time in a month today since i started using it, thats a record, i used to be reseting it daily!
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29-Apr-2007, 05:00 PM #9
Daredeval756....

I wasn't saying your method is wrong, if it fixed it or made it MUCH better, then it is a good start. However, since it is a business environment, the source needs to be identified and fixed completely. I.e. If it is some type of hack attack, then they need to get some type of protection in place; if the NIC is going bad, then they need to get that fixed!

I'm sorry to hear your connection bombed! However, like you said, once every now and then is much better than daily!

Thanks! Shane
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Daredeval756 Daredeval756 is offline
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29-Apr-2007, 05:18 PM #10
yes i do fully understand that, i am all for idnetifying the problem, this is just a quick fix, i simply do not have the time to fix my settings.


And yes it is a little less stress full not hang to reset it daily
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30-Apr-2007, 12:57 PM #11
OK... so I went through my network and I hope this helps explain the setup a bit more...

Each office is separated (but in the same building). I will outline what is in each office (as far as networking goes).

OFFICE 1:

This office has the 3 servers. As I mentioned before each is running server 2003, and 2 are file servers, the other is the main DNS server which is also our exchange server. Also in this office is 2 Netgear 10 port 10/100/1000 switches. One is currently not being used though.

Each one of the servers is connected to the switch. The main server as stated before is connected directly to the cable modem / router.

Also in the office is 7 PC’s (all connected to the switch as well). We also have 2 hubs (one a 4 port and one an 8 port) that 2 people use to connect more PC’s into. The 4 port is not used much (this person may plug their laptop in every once in a while). The 8 port, however, is used. This is the one that has the 3 PC’s connected that do the network renders.

Almost forgot there is one more 4 port hub that has our network printer and a PC connected to it, in this office.

OFFICE 2:

Office 2 has one of the netgear switches (which connects back to the office 1 switch). There are 6 PC’s and 1 printer connected to this switch.

OFFICE 3:

Office 3 like office 2 has one of the netgear switches (which connects back to office 2, and then back to office 1). Office 3 has 10 PC’s connected (so the entire switch is used up).

So hopefully that helps a little. I know enough about networking, but not everything. We actually had myself and a network consultant set this up (he did more of the setup, and showed me where everything is). Everything worked fine too for a good time (had these servers now for 2 years, but they were already 4 years old when we got them).

So basically we have a gig switch in each office. Office 3 is the furthest away, it connects to office 2 which connects to office 1 which connects to the server (main server). This server is then connected to the cable modem.

Usually (before our downtime started happening) I would have to mess with the servers maybe once every month or two (as far as net going down). It happens a lot more often now.

I am actually surprised it hasn’t gone down for a few days (last day was the 25th). I have not changed anything either. The only thing that is different is that I set up a server monitor that pings the server every 30 min and if it’s down sends me an email, and we have not done any network renders.

So with this info, does that help?

P.S. I do have access to the router. Firewall I believe is disabled, and a DMZ is setup for the server. I will have to double check on the firewall though (need to call comcast as I dont have a clue what I set the password to now).
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30-Apr-2007, 09:08 PM #12
That’s a pretty wild setup! Way too many HUBs running on your network, but that isn’t the problem at hand!

I would definitely check the cable modem with built in router to see what is going on. You are living extremely dangerous having your 2003 server in the DMZ. I think I would at least utilize the router’s firewall. No firewall on that server is just asking to be hacked!

I would first get access to your cable modem with built-in router and see what is setup and what is not setup. I would also keep a connection to that device and keep an eye on the log files! I would also setup my 2003 server to log EVERYTHING possible for a while, you will be more than busy checking the logs, but it may reveal your problem also.

You really need to get some protection on your network. Maybe a small Cisco PIX with the number of user allowed that you have on your network. You can get the Cisco 501 PIX really cheap.

I would bet that your problem still lies on your cable modem with built in router! However, you could be right that someone is hacking the crap out of your server too!

Keep a good eye on your cable modem/router combo! Track those logs!

Good luck!
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mikeaman mikeaman is offline
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04-May-2007, 01:48 PM #13
Thanks for the info... Yeah it is pretty wild. Also our server has 2 NIC cards... one connected to the router (for internet) and the other connects to our LAN.

I went ahead and looked on the router and also talked to comcast about it. So because we have a static IP i guess all the ports are always going to be open, so any "security" will need to come from something else. They do have a firewall, but I have to set it to disabled for our static or people cant connect in.

So I guess I will look into that firewall. One quick question. With the setup I have where would that firewall go (connect to)? Would the server connect to the firewall and the firewall then to the modem? One thing that might be hard is setting the # of allowed users. We have people that connect to our server via VPN.
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axis77 axis77 is offline
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04-May-2007, 05:43 PM #14
why cant you reenable the firewall and just poke a hole through it for vpn?
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