FTP is an easy way to transfer files.

But, a mistake in single step during the connection can lock you out and throw errors. One such error is FTP “socket error 11004“.

What’s socket? And, what’s this number in the error means? Well, we’ll see the answers to all these questions.

Fixing FTP issues of our customers is one of the common tasks that we do as part of our Outsourced Technical Support for web hosts.

Today we’ll discuss the top 3 reasons for this error and how we fix them.

What is FTP ‘socket error 11004’?

Before we go on, let’s first get an idea of this error.

A socket is the end point of communication between the client and the server, and this socket is bound to a port number.

In a normal FTP connection, the server listens on its socket. When the client makes a successful connection to the server, a new socket is created at the server end and client end to exclusively serve the client’s requests.

A socket error can occur if the above things aren’t going well or if something blocks the connection between the client and the server.

Liekwise, FTP socket error 11004 means that the name lookup(translation from domain name to IP address) has found a host, but no valid data.

FTP ‘socket error 11004’ – Causes and Solutions

We got a clear idea of this error. Now, let’s see the main reasons for the FTP ‘socket error 11004’ and how our Support Engineers fix them.

1) Typo in FTP hostname

Users should enter the FTP Host details to establish a connection and it can be the server hostname or IP address.

For example, to connect to a remote server server.hostname.com, users should enter the FTP host as server.hostname.com or ftp.server.hostname.com or the server IP address.

A typo in the FTP hostname/IP address or a missing Host field in the FTP settings can lead to this error. Similarly, even a single additional space in the hostname can also result in this error.

For example, one the of the common mistakes that we’ve noticed is that users erroneously enter the FTP hostname in their FTP clients as “ftp://ftp.domain.com“. But, the FTP server considers this to be an invalid host and rejects the connection.

Consequently, users see FTP ‘socket error 11004’

How we fix?

Firstly, our Support Engineer check the DNS connectivity of the FTP server using the below command.

dig ftp.domain.com

Further, we compare it with the user’s  FTP client settings. If a typo has been noted in the FTP hostname, we’ll immediately correct it.

For example, if the customer uses ftp://ftp.domain.com as the hostname, we ask the customer to change it to ftp.domain.com, domain.com or the domain’s IP address.

2) Bad DNS records of FTP host

Similarly, missing DNS records or incorrect DNS records for the FTP host can lead to this error.

This usually happens when you migrate the domain to a new server or change the DNS records of the domain.

Recently, we got a support ticket where the user complains that he can’t do FTP with hostname ftp.domain.com. Later, we identified that the domain was recently migrated and that the DNS records for ftp.domain.com are missing.

How we fix?

For DNS issues, our Support Engineers check the DNS connectivity of the FTP hostname using the telnet command. If we find any missing or incorrect DNS entries, we’ll correct the DNS settings of the domain to point to the correct server. During the propagation period, we suggest the customer to use the domain’s IP address as the FTP host.

3) Firewall blocks

Another possibility is firewall blocking the connection. Antivirus software or third party firewalls on the user’s PC can sometimes block connections.

How we fix?

We resolve this by asking the users to temporarily turn off all security applications(Windows firewall, software firewall, etc.) one by one. This helps us figure out exactly which app is causing the error, and fix its settings.

So, if you need help to solve your FTP issue, click here to get a Support Engineer to look into your issue.

Conclusion

In short, FTP “socket error 11004” can happen due to bad DNS records, firewall blocks, and more. Today, we’ve discussed the top 3 reasons for this error and how our Support Engineers fix them.