FTP server suddenly doesn't work anymore.

[mxnerd]

I'm trying to transfer file to a remote server which is on AT&T SBC network. It suddenly doesn't work anymore, yet I was using it yesterday.

I was using FileZilla server at the remote site. I used Filezilla FTP client or FireFTP add-on for FireFox, and neither worked.

From FileZilla server messages I could see that the the client seems logged in, but communication always stuck at PASV command, and it won't go any further.

I tried to use IE as FTP client and it won't login either.

Any idea? (I made sure Microsoft FTP server is not running)

 

[techmanc]

Can you connect to other FTP sites ok?

 

[mxnerd]

Yes, tested ftp.dlink.com and is perfectly fine. (It's anonymous though)

 

[techmanc]

Well next step would be to try to access the server from a different location although it sounds like the server is having a problem.

 

[spidey07]

Sounds like there is some network address translation or port address translation going on between the client and server.

 

[mxnerd]

WTF? Last night Charter network is down from midnight 12-2am. Before that, everything is working fine.

Now all FTP sites that require normal login doesn't work anymore. Anonymous login is fine.

I tried on 2 different machines (one Vista64, one XP32), different FTP clients (IE, FireFTP add-on, Maxthon, Standalone FileZilla), 2 FTP sites that require normal logins, and none of them works now.

Can Charter screw up so badly?

 

[JackMDS]

Port forwarding goes to the correct IPs?

 

[spidey07]

Originally posted by: mxnerd
WTF? Last night Charter network is down from midnight 12-2am. Before that, everything is working fine.

Now all FTP sites that require normal login doesn't work anymore. Anonymous login is fine.

I tried on 2 different machines (one Vista64, one XP32), different FTP clients (IE, FireFTP add-on, Maxthon, Standalone FileZilla), 2 FTP sites that require normal logins, and none of them works now.

Can Charter screw up so badly?

Sounds like an upgrade happened.

 

[mxnerd]

reboot workstations, cable modem, dd-wrt router and nothing works.

I did not change any username or password. I can login the free zymic.com web hosting service using the control panel through web browser, but FTP does not work anymore.

"530 Login authentication failed"

 

[mxnerd]

This is absolutely weird.

I create another FTP server on a Verizon network using FileZilla, same setting, same username, same password, same directory rights, and it works fine. But the other FTP server on SBC networks just won't work. Always stops at PASV command, and it looks like probably the trailing LIST command which list directory contents just won't execute or stucks there, even the username has every rights for that folder.

*EDIT*

Uninstalled the FileZilla server on SBC network, delete all settings. Reinstall FileZilla server (new download), recreate user, password and directory rights. Same thing.

FileZilla Cilent message

Status: Resolving address of remote.mydomain.com
Status: Connecting to 6x.xxx.xxx.xxx:21...
Status: Connection established, waiting for welcome message...
Response: 220-FileZilla Server version 0.9.30 beta
Response: 220-written by Tim Kosse (Tim.Kosse@gmx.de)
Response: 220 Please visit http://sourceforge.net/projects/filezilla/
Command: USER admin
Response: 331 Password required for admin
Command: PASS **********
Response: 230 Logged on
Command: SYST
Response: 215 UNIX emulated by FileZilla
Command: FEAT
Response: 211-Features:
Response: MDTM
Response: REST STREAM
Response: SIZE
Response: MLST type*;size*;modify*;
Response: MLSD
Response: UTF8
Response: CLNT
Response: MFMT
Response: 211 End
Status: Connected
Status: Retrieving directory listing...
Command: PWD
Response: 257 "/" is current directory.
Command: TYPE I
Response: 200 Type set to I
Command: PASV <----------- stucks here. After a while, then be kicked out.

 

[spidey07]

You didn't pay attention when I said it sounds like NAT is involved. That's what happens when NAT/PAT is in the path - you can't open the data channel. Google "FTP and NAT".

 

[mxnerd]

Originally posted by: spidey07
You didn't pay attention when I said it sounds like NAT is involved. That's what happens when NAT/PAT is in the path - you can't open the data channel. Google "FTP and NAT".

Thanks. But I did not change networks at all. Will ISP change their networks and render business customer's FTP unusable?

Anyway, thanks again and I'll search "FTP and NAT."

 

[spidey07]

It's happened before. Or it could actually be YOUR router or network gear/firewall. But the most common cause of a control channel not working is NAT/PAT.

If you're a business customer you should just call support and get it fixed.

 

[mxnerd]

I have read http://www.enterprisedt.com/pr...pthroughafilewall.html

It turns out that now I have to use active mode, not passive mode for FTP servers for SBC & Verizon networks, both are behind NAT routers. if I change FTP client to active mode, then it works.

Before yesterday, i was able to use passive mode. After probable Charter's upgrade, I can't use passive mode anymore.

Most FTP client use passive as default. And it does not work now. How come? It looks like more flexible.

zymic.com FTP still does not work, but that could be their problem. Since a lot of users are aloso complaining.

*EDIT*

While I was changing FileZilla settings, i saw FileZilla is sending something like IPv6 message?

|x|xxxx::xxxx:xxxx:xxxx:xxxx%xx|xxxxx| (x represents hexdecimal)

Does it looks like ISPs are starting to send IPv6 packets even for those who are still on IPv4 networks?

Is it possible that's what happened to cause all this mess?