Can connect through internet but not network - error 421

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Noor
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Can connect through internet but not network - error 421

Post by Noor » Thu Aug 11, 2011 6:12 am

Hello,

Searched through the forum archives but it seems my problem is the exact opposite of most...

My setup: Running Cerberus on a computer connected to a Qwest Q1000 modem. Computer has a static IP, all necessary ports are forwarded, Windows Firewall has exceptions for those ports, etc. Then, I use a service called No-IP to link my dynamic WAN with a stable DNS name so I can link to it on my website for people to access and it will never change (it is a public FTP open to all). People click the link, No-IP redirects them to my modem's WAN, it port forwards to the server, everyone is happy. Works 100% fine with every computer I've tested off the network.

However, no matter what I've tried, none of the computers that share the same network as the FTP server can access it through the No-IP DNS link. I can access it from these computers by keying in the internal IP of the server (ftp://192.168.***.***), but if I click on the DNS link, I get "421 Login incorrect." I'm not sure it even has anything to do with Cerberus; the Cerberus log shows absolutely nothing when this happens, so it seems like the query never even gets to the FTP server. I've turned off and on just about every option that seems related in Cerberus and my modem settings, with no effect. I'm stumped, and just don't know what the problem could be or what to try next.

The reason I really want this to happen is that up until about a week ago I was using Gene6 FTP server with this same setup (No-IP through a modem), and everyone could access it just fine, both on and off the network. So it seems to me like it should be possible, and it would be really helpful for me. However, since then I have tried Filezilla and then Cerberus, and I couldn't/can't get it to work with either of them. I also made a lot of changes all at once (upgraded from Windows XP 32bit to Windows 7 64bit, got a new Qwest service plan and modem, and switched to a new FTP program) so it is hard for me to know what precisely the culprit might be, or if one of these changes now makes this impossible.

So, any thoughts on what I could try, or why this isn't working? Other places I could/should post this question that could help me even better? More info you need to know to help me troubleshoot? If you want to do some of your own testing, the DNS for my FTP is: ftp://maitreya.no-ip.info/ . Thanks very much, and hope to hear from someone soon!

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Serin
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Re: Can connect through internet but not network - error 421

Post by Serin » Thu Aug 11, 2011 10:35 am

Another strange things is that Cerberus doesn't return a '421 Login incorrect.' message for anything. It almost seems like that might be coming from another server. Do you happen to have the old server still up and running somewhere? Perhaps your internal network clients are caching the old server IP for some reason? I'm reaching, but the fact that you are getting a message back seems to indicate you are hitting some FTP server, and if there is nothing in the Cerberus log...

Noor
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Re: Can connect through internet but not network - error 421

Post by Noor » Fri Aug 12, 2011 2:15 am

Thanks for the reply, it is good to know that it is definitely not Cerberus but something else.

The other server should be nowhere to be found, I did a clean Windows 7 install on a different formatted hard drive, as well as upgraded my modem and service plan, so pretty much everything was changed. I do have an Asus RT-N56U router connected to the modem which has a built in FTP service, so when you said that, I thought it might be interfering, but I tried disconnecting the router from the modem and nothing changed, so I am assuming it is not that either.

I also called Qwest today and talked to a specialist on the Q1000 modem to find out if there is anything built into it that could be interfering/blocking. He said absolutely not, and that the problem could not be the modem.

Here's something interesting I am just noticing: On Firefox, when I try to access the FTP, it gives me the 421 Login incorrect error. However, on IE, it brings up the login and password screen on an endless loop (no matter what I type in it is not accepted and just pops back up again). And on Chrome, it says "Error 324 (net::ERR_EMPTY_RESPONSE): The server closed the connection without sending any data." We have had the endless loop error (on IE) before, on our old FTP program, and it ended up being a problem with the Windows Firewall. The modem tech support guy I called also told me he would guess it was Windows 7 messing me up (he wasn't a fan of the program). So I guess I will do some tinkering and researching about Windows 7 firewall and FTP troubles to see if something is messed up there. Any other comments, suggestions, information, etc. appreciated.

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Re: Can connect through internet but not network - error 421

Post by Serin » Fri Aug 12, 2011 10:45 am

Actually, do a Google search for "421 Login incorrect" message. There are several interesting pages that come up, and all mention a QWest modem being recently replaced. Does the QWest modem have a built-in FTP server?

Noor
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Re: Can connect through internet but not network - error 421

Post by Noor » Sun Aug 14, 2011 6:01 am

Here we go, I think I've figured out the problem. I tried to connect using FileZilla client, thinking that the log might give me info on what's happening. Here it is:

Status: Resolving address of maitreya.no-ip.info
Status: Connecting to 174.28.66.195:21...
Status: Connection established, waiting for welcome message...
Response: 220 Ftp firmware update utility
Command: USER anonymous
Response: 331 Password please.
Command: PASS **************
Response: 421 Login incorrect.
Error: Could not connect to server

I saw this in another post on here: http://www.cerberusftp.com/phpBB3/viewtopic.php?t=1344 . According to that post, this means that the modem thinks I am trying to update its firmware, so it asks for the name and password for the modem, and when it is not given that it rejects the connection. I confirmed this by entering in my modem's admin username and password, and this is what I got:

Status: Resolving address of maitreya.no-ip.info
Status: Connecting to 174.28.66.195:21...
Status: Connection established, waiting for welcome message...
Response: 220 Ftp firmware update utility
Command: USER ********
Response: 331 Password please.
Command: PASS ********
Response: 230 User logged in.
Command: SYST
Response: 215 UNIX Type: L8
Command: FEAT
Response: 500 Unknown command: "FEAT"
Status: Connected
Status: Retrieving directory listing...
Command: PWD
Response: 500 Unknown command: "PWD"
Error: Failed to retrieve directory listing

Of course, this does not work either as I am trying to get to my FTP, not login to my modem's firmware update utility. But now at least I know for sure what's going on.

The question is, is there anything I can do about this? I already tried switching the FTP port from 21 to something else up above 1024, and it didn't seem to make a difference. Is this something I just can't get around, and I need to put my FTP on a different modem to make it work? I might call the modem tech support back again to see what they have to say, but any ideas would be appreciated. Thanks.

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Re: Can connect through internet but not network - error 421

Post by Serin » Mon Aug 15, 2011 10:25 am

I recommend looking for an option to disable the internal FTP server on the modem/router. However, changing the FTP port for Cerberus and changing the port forwarding rules should have resolved the issue if you can't disable the internal FTP server on the modem. I would contact the vendor.

Noor
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Re: Can connect through internet but not network - error 421

Post by Noor » Fri Aug 19, 2011 11:10 pm

I just wanted to say thank you for all your help. I am using the FTP on another router now and it works 100% perfectly. I may still contact Qwest and see if we can get that original router working, or maybe get a replacement, but now that I know the problem and the solution I'm all set. Thanks again.

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Re: Can connect through internet but not network - error 421

Post by Serin » Sat Aug 20, 2011 11:24 am

Great, I'm happy I could help.

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