Why is my machine unable to mount my SMB drives ("CIFS VFS: Error connecting to socket. Aborting operation", return code -115)?

Question

I have a machine running Precise (12.04 x64), and I cannot mount my SMB drives. It used to work (a week or two ago) and I didn't touch fstab! The machine hosting the shares is a commercial NAS, and I'm not seeing anything that would indicate it's an issue with the NAS.

I have an older machine which I updated to Precise at the same time (both fresh installed, not dist-upgrade), so should have a very similar configuration. It is not having any problems. I am not having problems on windows machines/partitions either, only one of my Precise machines.

The two machines are using identical entries in fstab and identical /etc/samba/smb.conf files. I don't think I've ever changed smb.conf (has never mattered before).

My fstab entries all basically look like this:

//<share_path>       /media/<share_name>        cifs  credentials=/home/downbeat/.credentials,iocharset=utf8,uid=downbeat,gid=downbeat,file_mode=0644,dir_mode=0755 0 0

Here's the dmesg output on boot:

[   51.162198] CIFS VFS: Error connecting to socket. Aborting operation
[   51.162369] CIFS VFS: cifs_mount failed w/return code = -115
[   51.194106] CIFS VFS: Error connecting to socket. Aborting operation
[   51.194250] CIFS VFS: cifs_mount failed w/return code = -115
[   51.198120] CIFS VFS: Error connecting to socket. Aborting operation
[   51.198243] CIFS VFS: cifs_mount failed w/return code = -115

There are no other errors I see in the dmesg output.

Again, it used to work; now it doesn't. Very similarly configured machine works (but some packages are out of date on the working machine). The NAS has only one interface/IP address, nmblookup works to find it's IP from it's hostname (from the machine with the issue) and it responds to a ping. Please any help would be great.

Answer 1

I found that switching off IPv6 solved a very similar problem for me. My Ubuntu 12.04 box is hooked up to an enterprise network dominated by Windows users and I don't have any authority over the server. Following the tutorial at http://www.noobslab.com/2012/05/disable-ipv6-if-your-internet-is.html solved my problem. (Save a click: Edit /etc/sysctl.conf to insert three lines of the form "net.ipv6.conf.*.disable_ipv6 = 1", replacing * with "all", "lo", and "default"; then give the shell command "sudo sysctl -p".)

Answer 2

My internal IP ended up in my NAS's blocklist. I removed it; problem solved. Used smbclient to troubleshoot.

EDIT: I am much more familiar with GNU/Linux these days, and if I were attempting to debug this today, I would check out hosts.deny and iptables, one of which (or both) is likely used to implement the blocklist/blacklist in my now decommissioned commercial NAS.

Answer 3

In my case, the Windows machine I was trying to mount a shared drive from had suddenly decided it was on a public network, and was blocking all access. Telling it the network was private allowed me to connect again.