If it is an older WinXP share you are attempting to mount, then you will need to enable NTLMv1 authentication by including the sec=ntlm or sec=ntlm1. See mount.cifs for further use of the sec= option.
If it is an older WinXP share you are attempting to mount, then you will need to enable NTLMv1 authentication by including the sec=ntlm or sec=ntlm1. See mount.cifs for further use of the sec= option.