I am using a MacBook Pro with OS X 10.10.3. I am a developer and I use FTP on a regular basis. However I am new to OS X. It was working fine but suddenly FTP stops working for all FTP clients on my Mac for any server, even for ftp://ftp.mozilla.org/. I use NetBeans and use its most native Java based client. I tried with Firebug, FileZilla, Firefox, Chrome and OS X's native Finder client. I tried with Terminal as well — the response is:

Tousifs-MBP:~ tousifosman$ ftp -v ftp://ftp.mozilla.org/
Connected to ftp.mozilla.org.
421 Service not available, remote server has closed connection.
ftp: Can't connect or login to host `ftp.mozilla.org'

However I am able to connect to all the servers from my Windows platform.

  • What does the Ping shows. In Terminal type Ping and let it run. I get 20ms. – Ruskes Jun 7 '15 at 17:14

The occurred due to my local wifi network. It was some how blocking ftp. Replacing the router solved my problem


I do not normally use the FTP but here is the result for comparison.

~  ftp -v ftp://ftp.mozilla.org/
Connected to ftp.mozilla.org.
220-   ftp.mozilla.org / archive.mozilla.org - files are in /pub/mozilla.org
220-   releases.mozilla.org now points to our CDN distribution network and no longer works for FTP traffic
331 Please specify the password.
230-   ftp.mozilla.org / archive.mozilla.org - files are in /pub/mozilla.org
230-   Notice: This server is the only place to obtain nightly builds and needs to
230-   remain available to developers and testers. High bandwidth servers that
230-   contain the public release files are available at http://releases.mozilla.org/
230-   If you need to link to a public release, please link to the release server,
230-   not here. Thanks!
230-   Attempts to download high traffic release files from this server will get a
230-   "550 Permission denied." response.
230-   Low-traffic files, including SeaMonkey releases, are OK.
230 Login successful.
Remote system type is UNIX.
Using binary mode to transfer files.
200 Switching to Binary mode.

PS, I use FF as browser.


Had the same issue... it turned out I had a corrupted NAT table in my router so I could send requests to FTP servers but I did not receive anything...

One quick reboot of the router and computer later everything is fine. Very weird as everything else BUT the FTP connection worked just fine.

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