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Re: Internel Access & Email Problems (still!!)-getting desperate

 
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Richard Darling
Trusted Contributor

Internel Access & Email Problems (still!!)-getting desperate

The installer of my SBS 4.5 can't get email/internet access to work consistently.

Background (all ips are bogus to protect the innocent):
I am adding the SBS to an existing network that has two UNIX boxes. All of the PCs were setup with static IPs. They are all on an internal network of 194.0.0.0.

We didn't go with the default IP for the server, but gave it 194.0.0.5 - saves me from changing all the IPs on the UNIX boxes, PCs, printers, etc. I am wondering if he has setup the NIC cards properly? The internal network card is:

IP address: 194.0.0.5
subnet mask: 255.255.255.0
(no default gateway)
The external card is:

IP addr: 194.0.0.4
subnet: 255.255.255.0
default gateway: 194.0.0.95

The internet is accessed thru a DSL router with the internal IP of 194.0.0.95, which has been working fine for users accessing the internet/email directly from their PCs, not going through the SBS. The UNIX box is also accessed thru the router. The external address of the router is 94.23.24.1.

The router settings are:
194.0.0.4 94.23.24.1 pop3
194.0.0.4 94.23.24.1 smtp

I can't get users to get mail. Whenever I open IE the message at the bottom is "detecting server1.." (which is the name of the server), and then I get the message that the page can't be dispalyed. I can get the browser to work by entering either of the NIC card addresses(194.0.0.4 or .5) in the "Tools", "internet Options"; "connections"; "LAN settings"; "PROXY settings" field. Every time I attempt to check user mail I get the message that the pop3 server can't be found. If I attempt to ping the pop3 server by name I get a bad IP address message.

Any help is greatly appreciated. Picked up the SBS book and surfed the msn sites...no help with this problem. I am a newbie with the SBS...any help greatly appreciated...and I always assign points!!!

RD
rdarling@southwickclothing.com
8 REPLIES 8
Bryce Dunn
Valued Contributor

Re: Internel Access & Email Problems (still!!)-getting desperate

Are you using proper private IP's for you local lan? (eg 192.168.x.x, 10.x.x.x etc, 172.???), otherwise the router might be sending stuff to the real owner of those IP's?
Richard Darling
Trusted Contributor

Re: Internel Access & Email Problems (still!!)-getting desperate

Bryce the address is 192.100.100.xxx; I inherited it so I had alwys assumed that it was OK...how can I check that?
rdarling@southwickclothing.com
Joseph T. Wyckoff
Honored Contributor

Re: Internel Access & Email Problems (still!!)-getting desperate

You said...

IP address: 194.0.0.5
subnet mask: 255.255.255.0
(no default gateway)

The external card is:

IP addr: 194.0.0.4
subnet: 255.255.255.0
default gateway: 194.0.0.95


---
This look like a problem configuration to me. Based on your subnet mask, both of your cards are on the same IP subnet, 194.0.0.x

You will probably either need to tighten the subnet masks, or change one of the IP's.

----You can leave the subnet mask alone, and change the IP

IP address: 194.0.1.5
subnet mask: 255.255.255.0
(no default gateway)

>>> Thus this is on subnet 194.0.1.x

The external card is:

IP addr: 194.0.0.4
subnet: 255.255.255.0
default gateway: 194.0.0.95

>>> Thus this is on subnet 194.0.0.x

---In principle you could use those IP's, but you would need to make some adjustments

IP address: 194.0.0.5
subnet mask: 255.255.255.248
(no default gateway)

>>> Thus this is on subnet 194.0.0.x
where valid x is 1,2,3,4,5,6

But actually this would still conflict because .4 is in fact still on the same subnet - and the router would not be!


IP addr: 194.0.0.4
subnet: 255.255.255.248
default gateway: 194.0.0.95

---But this would likely work...

IP addr: 194.0.0.94
subnet: 255.255.255.248
default gateway: 194.0.0.95

---
Now subnetting and supernetting, and load sharing can be complex stuff... but there is a pretty good chance that you are just having this basic mis-configuration...

The two IP addresses must normally be on distinct subnets - and the subnet mask helps you define what a subnet is...

If the subnets overlap logically - routing rules get all goofed up at the TCP level.

Netbios (WINS, etc.) stuff gets confused too... if the two network cards are actually onthe same physical network.

Good Luck.
Omniback and NT problems? double check name resolution, DNS/HOSTS...
Joseph T. Wyckoff
Honored Contributor

Re: Internel Access & Email Problems (still!!)-getting desperate

Something you said has caught my attention... but I cannot quite place what.

You mention two applications... web / browser services and SMS?

Web browser stuff is likely to use TCP / Sockets kinds of mechanisms - DNS and the HOSTS files.

SMS, on the other hand, is almost pure Microsoft... and is very likely to use Microsoft native mechanisms - WINS, broadcast / peer resolution, and LMHOSTS.

Name resolution stuff like that can be tricky...

Poke around tho, and compare HOSTS (UNIX-ISH) and LMHOSTS (NT-ish) files, NSLOOKUP (pure DNS) and PING (can resolve from lots of different places) - you may be suprised to find that the answers from each of these tools are inconsistent. Application behaviour would, then be inconsistent too.
Omniback and NT problems? double check name resolution, DNS/HOSTS...
Bryce Dunn
Valued Contributor

Re: Internel Access & Email Problems (still!!)-getting desperate

I assume that you are using the DSL router to do some kind of NAT or masquerating and that your internal machines are not supposed to have public IP addresses. If this is the case then it is good practice to use private IP addresses on your local LAN as set out by RFC #1918

These address ranges are:

10.0.0.0 - 10.255.255.255 (10/8 prefix
172.16.0.0 - 172.31.255.255 (172.16/12 prefix)
192.168.0.0 -192.168.255.255 (192.168/16 prefix)
Richard Darling
Trusted Contributor

Re: Internel Access & Email Problems (still!!)-getting desperate

Joseph and Bryce - thanks for the information -let me do some more poking around - any other thought appreciated....

I inherited the 192.100.100.xxx/24 subnet. The system here was originally an HP3000 that was upgraded to an HP9000 g40, which I have upgraded to an HP9000 L1000. The users currently access the network either through dumb terminals or telnet from a Novell Network.

All the IP addresses are static so I would have to change all the addreses of the L1000, the PCs, terminal servers, printers, print servers, etc.

Not a fun job, but if this will help sove this problem I should do it.
rdarling@southwickclothing.com
Bryce Dunn
Valued Contributor
Solution

Re: Internel Access & Email Problems (still!!)-getting desperate

I am a bit unsure of your current network setup so any more information that you can give would help. If you are setting up a machine with an internal and external network card it is normally very hard (and not really advisable) for both interfaces to be on the same network. I think someone else has said somthing to that effect. Otherwise the routing table gets screwed up because it is never quite sure which interface it should be going out on unless you set up static routes for every machine in the network, which is a bad idea.

if you are tyring to do:

router <=> SBS <=> LAN

then can you change the network between the router and the SBS?

for instance (with dummy ip's)

router:
extif = 94.1.2.3
intif = 192.168.1.1

SBS:
extif 192.168.1.2
exitif 192.168.2.1
gw: 192.168.1.1

Lan:
192.168.2.0/24
gw 192.168.2.1

if this was the case you could probably quite safely leave your non standard internal IP's.

The only problem with this example is that I am not 100% sure where the SBS fits in and where I have put it is just a guess.

If you just want to have it on the lan and do port forwarding then It wouldn't really need 2x network cards.

The other problem that you will have if you use a non standard internal network range is that if you try to send packets to the real owner of that block then they will float around in your network. THis would be especially bad if the real owner of those IP's was an important customer etc and he had his mail exchanger server sitting on one!

It is possible to find out who owns a block of ip's using whois.

Good Luck
Richard Darling
Trusted Contributor

Re: Internel Access & Email Problems (still!!)-getting desperate

Bryce, I have the email issue resolved. I found that the Domain in the DNS config. of network neighborhood was pointing to our domain name; southwickclothing.com; not the ISP's DNS...also, I assigned an IP address to the external card of 192.168.x.x, which is not on the same subnet as the rest of the network. Thanks for your help - it pointed me in the right direction (s??)
rdarling@southwickclothing.com