Cannot connect to Mac computer via smb in Ubuntu 16.04

I have the same problem using Xubuntu 16.04 and Mac 10.11.6. The best answer I could find Access OS X file share from Ubuntu

If using SMB then with El Capitan Apple have recently implemented a new change intended to enhance security. This involved signing all the network packets. Some SMB clients cannot cope with this feature although I would expect a Linux machine running a recent version of SAMBA4 to be able to. It may require enabling a matching option in SAMBA. It is however possible to turn this feature off on the Mac server by doing the following.

sudo defaults write /Library/Preferences/SystemConfiguration/com.apple.smb.server SigningRequired false

and

writing the following to /etc/nsmb.conf

[default]
signing_required=no

Apple officially has a how-to article of above method here.

However, I still cannot access Mac SMB share from my linux.

Current workaround is to use AFP protocol and Netatalk according to this guide

I found the working solution from Apple discussion (which involves mounting with specific option)

The key is the "nounix,sec=ntlmssp" options

So, I have to mount with

sudo mount.cifs //mac.server.address.ofcomputer /mnt/Mac -o nounix,sec=ntlmssp,username=myusername

For smbclient, you may need --option="ntlmssp_client:force_old_spnego = yes" as suggested on the samba-technical mailing list.

This now lists shares on a Mac OSX server:

smbclient -U$user%$password -L $mac_osx_host --option="ntlmssp_client:force_old_spnego = yes"

For mounting, you may need to add the nounix,sec=ntlmssp options as already suggested here.

I didn't need to change any configuration on the Mac OS X side.