When trying to access a samba share with smblcient -L //localhost from my local Samba Server, I get after a delay the error message

protocol negotiation failed: NT_STATUS_IO_TIMEOUT

What are the debugging steps to get to the root of this problem systematically?


For my own training purposes I am setting up a simple shared folder over a samba server on a CentOS 7 virtual machine.

I added following lines to the smb.conf file and created the directory, selinux configuration and firewall rule.

comment = sambashare
path = /sambashare
public = yes
writable = yes
write list = +users

3 Answers 3



You haven't configured DNS name resolution for your servername and have to set the servername either in the /etc/hosts manually or in your DNS server.

Debug process:

In the case of NT_STATUS_IO_TIMEOUT try to use a network traffic analyser like tcpdump. (ex. tcpdump -i >network interface<)

If following lines appear:

07:57:54.726390 IP > 20986+ A? server.example.local. (38)
07:57:54.726648 IP > 44015+ AAAA? server.example.local. (38)
07:57:54.727069 IP > 34381+ PTR? (39)
07:57:54.732388 IP > 20986 NXDomain* 0/0/0 (38)
07:57:54.733400 IP > 34381 NXDomain* 0/0/0 (39)
07:57:54.733642 IP > 24458+ PTR? (39)

This means that the smbclient isn't able to resolve the servername server.example.local which is a DNS resolution problem.


I have added the following line in /etc/samba/smb.conf and it works :

guest ok  = yes

in the section of my share parameters.

Then I've restarted the service and it works perfectly

  • 7
    For future readers: this gives everyone on the network guest access to your shares without a password, don't use guest ok if you care about security
    – Paradoxis
    Oct 23, 2019 at 10:57

For me on Fedora Rawhide 33 I needed to use one the following in "/etc/samba/smb.conf":

client min protocol = CORE


client min protocol = NT1

and define the host in "/etc/hosts":

<ip_address>   REMOTE_DEVICE

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