Mail stopped working

[Zathros]

After getting my mail server up and it running for several days, email suddenly stopped being forwarded. I was having my router forward all email to the linux box, and it in turn to my sco box. (The linux box is serving as a firewall)

I checked the setup, gateway, portforwarding etc... and everything seems fine. I havant stopped and restarted sendmail since I'm using protforwarding.

What would cause this to just stop working?

 

[GunJack]

I'm not clear on your setup but should be able to help if you clear a few things up.
1. What do you mean by you're having your router forward mail as this is not a normal router function?
2. I'm not familiar with protforwarding. Is this a program you're running?
3. Is the linux box running Sendmail (or other) so that it accepts mail from the outside and then forwards to your sco box?

GJ

 

[Zathros]

>I'm not clear on your setup but should be able to help if >you clear a few things up.
>1. What do you mean by you're having your router forward
>mail as this is not a normal router function?

I'm probably not using the correct terminology since I'm .fairly new to networking. Or netopia dsl router has a config setting that forwards/diverts/passes through all traffic on certain ports to the specified ip address. Port 25 is set to the internal ip of the linux box.

>2. I'm not familiar with protforwarding. Is this a >program you're running?

I don't do the original config on the linux box so I can only tell you what my vendor told me to change. In my /sbin directory there is a portfw.rules executable that you enter the ip addresses you want the ports to automatically forward to. For instance:

#script----------portfw.rules
#Forward specific packets from firewall's outside port to an inside
#destination.

#Clear the port forwarding table

/sbin/ipportfw -C

#Sample config

#Forward SMTP and POP3 packets to inside mail server

/sbin/ipportfw -A -t xxx.xxx.xxx.xxx/25 -R yyy.yyy.yyy.yyy/25
/sbin/ipportfw -A -t xxx.xxx.xxx.xxx/110 -R yyy.yyy.yyy.yyy/110

# (x is the linux box and y is the SCo server)

>3. Is the linux box running Sendmail (or other) so that >it accepts mail from the outside and then forwards to your >sco box?

I'm not sure if sendmail is running on it or not. It doesn't do the mail serving (I thought it did and refer to it incorectly as a mail server, but it used to be more of just a proxy server). Sendmail doesn't show up as a process.

 

[GunJack]

Ok, that's kinda what I was suspecting. There are 3 possible problem points obviously, the Netopia, the linux box, or the mail process on the sco box. I would start with the sco box. Try telnetting to port 25 on your sco box an see if it responds with a welcome message. If it does, I would disconnect and try the same thing with the linux server's IP. I'm new to firewall configs but I believe telnetting to port 25 on the linux box should give you the same mail server greeting from the first step. If your network is divided into two subnets, you may have to change your workstation ip for this. If this step works, I would then try the same thing from the outside. I can do this (assuming you're connected to the Internet) if you give me the IP. If all of these work and you're still not getting mail. I would suspect a config problem on the mail server as it would indicated that there is a connection to the server and it is responding.

Let me know what you find.
GJ

 

[Zathros]

The router and the SCO box are fine. I pointed the router to the SCO machine and mail is flowing again. But I want to get my firewall back up as soon as a wangle another IP out of my DSL provider. (which means I need mail on it to work)

I issued the sendmail stop sendmail start command on the linux box, (from the /etc/rc.d/init.d directory) and it seemed to work, but sendmail doesnt show as a process.

I also rebooted the linux box with no change on the problem. So I'll keep digging....

 

[GunJack]

Sendmail won't show up as a process if you just issues "ps", you'll need to issue "ps ax" or "ps ax | grep sendmail" to screen out all the others. If your firewall is configured to pass smtp packets onto the sco box though, you shouldn't need sendmail running on the linux box anyway. I'm guessing it's a problem with your proxy config at this point. Did you make any changes to it just before the problem started (annoying question I know)?

One thing I just thought of is they may have changed your IP address or even subnet mask and this may be causing your firewall rules to deny the packets. I don't think the rules above would be affected by this but do you have any rules of higher precedence that might have a stricter ip or mask filter?

GJ

 

[Zathros]

Yes you're right, I forgot about some of the ps flags. I had written a script long ago called 'process' for my sco box that handles a lot of that for me.

At any rate...

Sendmail is running...

I think the best thing I can do right now is go all the way through my config and look at everything. I may need to blow everything away and start over. I may need to hire some body to fix it. <gasp>

Hmmmm... now that is intersting... I just sent mail out to a dial up account I have and it wnt through. So mail can go out, but something has screwed it up coming in...

But to answer your questions. No changes prior to the problem I know of. They haven't changed my IP, I only have the router on an external IP, all others are for internal only, they can't be seen on the internet.

Well wait, I did change the gate way for the machine to the router instead of the SCO box. Would that do it?

 

[GunJack]

I wouldn't think so but it's possible. I'd change it back and just see. I would think the way you have it now is how it should be setup but if it does make a difference, it will at least give a clue to the problem.

Do you have both machines on the same internal subnet? If the linux machine is configured such a way (i.e. wrong mask) that it thinks the sco box is on a different subnet, that might be your problem. If so, this would likely be related to the gateway change. If the linux box thinks it has to go across a gateway to get to the sco box and the sco box is configured as the gateway, it might work. If you changed the gateway and the linux box tried to go through the Netopia to get to the sco box, this would likely fail.

Let me know your ip config on both machines (ip,gw, &amp; mask) as depending on how you have them configured, I would run tcpdump and watch what's happenning on the wire.

GJ