NSMB.CONF(5) File Formats Manual NSMB.CONF(5)

nsmb.conf — configuration file for SMB requests

The nsmb.conf file contains information about the computers and shares or mount points for the SMB network protocol.

The configuration hierarchy is made up of several sections, each section containing a few or several lines of parameters and their assigned values. Each of these sections must begin with a section name enclosed within square brackets, similar to:

[section_name]

The end of each section is marked by either the start of a new section, or by the abrupt ending of the file, commonly referred to as the EOF. Each section may contain zero or more parameters such as:

[section_name]
key=value

where key represents a parameter name, and value would be the parameter's assigned value.

The SMB library uses the following information for section names:

[default]
[SERVER]
[SERVER:SHARE]

Possible keywords may include:

Section Default Comment
A B C Values
addr - + - DNS name or IP address of server
nbtimeout + + - 1s Timeout for resolving a NetBIOS name
minauth + + - NTLMv2 Minimum authentication level allowed
port445 + + - both How to use SMB TCP/UDP ports
streams + + + yes Use NTFS Streams if server supported
soft + + + no Force all mounts to be soft
notify_off + + + no Turn off using notifications
kloglevel + - - 0 Turn on smb kernel logging
protocol_vers_map + + - 7 Bitmap of SMB Versions that are enabled
signing_required + + - no Turn on smb client signing
signing_alg_map + + - 3 Bitmap of SMB 3.1.1 signing algorithms that are enabled
signing_req_vers + + - 6 Bitmap of SMB Versions that have signing required
validate_neg_off + + - no Turn off using validate negotiate
max_resp_timeout + + - 30s Max time to wait for any response from server
submounts_off + + + no Turn off using submounts
dir_cache_async_cnt + + - 10 Max async queries to fill dir cache
dir_cache_max + + - 60s Max time to cache for a dir
dir_cache_min + + - 30s Min time to cache for a dir
max_dirs_cached + + - Varies Varies from 200-300 depending on RAM amount
max_cached_per_dir + + - Varies Varies from 2000-10000 depending on RAM amount
netBIOS_before_DNS + + + no Try NetBIOS resolution before DNS resolution
mc_on + + - yes Turn on SMB multichannel (allow more than one channel per session)
mc_max_channels + + - 9 Max channels between client and server
mc_srvr_rss_channels + + - 4 Max RSS channels per server interface
mc_clnt_rss_channels + + - 4 Max RSS channels per client interface
mc_prefer_wired + + - no Prefer wired NIC's over wireless in multichannel mode
encrypt_cipher_map + + - 15 Bitmap of SMB 3.1.1 encryption algorithms that are enabled
force_sess_encrypt + + - no Force session encryption
force_share_encrypt + + - no Force share encryption
connect_to_sharedisk + - - yes Allow connection to a server in disk share mode
comp_algorithms_map + + - 0 Bitmap of compression algorithms that are enabled
comp_chaining_disable + + - no Disable chained compression
comp_io_threshold + + - 4096 Min IO size to use compression (4096 - 1048576)
comp_chunk_len + + - 256KB Chained write chunk size for processing
comp_max_fail_cnt + + - 5 Max times write compression can fail before disabling for that file
comp_exclude_list + + - Comma separated list of file extensions to not compress
comp_include_list + + - Comma seperated list of file extensions to override default exclusion list

The minimum authentication level can be one of:

Kerberos - NTLMv2, NTLM, LM, and plain-text password authentication are not attempted.
NTLMv2 - Kerberos authentication is attempted if a Kerberos token can be obtained, otherwise NTLMv2 authentication is attempted; if the server doesn't support encrypted passwords, the authentication fails.
NTLM - Kerberos authentication is attempted if a Kerberos token can be obtained, otherwise NTLMv2 authentication is attempted and, if that fails, NTLMv1 authentication is attempted, with zeroes in the LM hash; if the server doesn't support encrypted passwords, the authentication fails.
LM - Kerberos authentication is attempted if a Kerberos token can be obtained, otherwise NTLMv2 authentication is attempted and, if that fails, NTLMv1 authentication is attempted, including the LM hash; if the server doesn't support encrypted passwords, the authentication fails.
none - The same as lm except that, if the server doesn't support encrypted passwords, plain-text passwords are used. Required for servers that don't support extended security.

(Note: "NetBIOS" as used below means "NetBIOS over TCP/IP.")

"How to use SMB TCP/UDP ports" can be one of:

Attempt to connect via port 445. If that is unsuccessful, try to connect via NetBIOS.
Do not attempt to connect via port 445.
Attempt to connect via port 445. If that is unsuccessful, do not try to connect via NetBIOS.

"Bitmap of SMB Versions that are enabled" can be one of:

7 == 0111
SMB 1/2/3 should be enabled
6 == 0110
SMB 2/3 should be enabled
4 == 0100
SMB 3 should be enabled

"Bitmap of SMB Versions that have signing required" can be one of:

Signing required for SMB 1/2/3.
Signing required for SMB 2/3.
Signing required for SMB 3.

"Bitmap of SMB 3.1.1 signing algorithms that are enabled" can be one of:

AES-128-GMAC/AES-128-CMAC should be enabled
AES-128-CMAC should be enabled

"Bitmap of SMB 3.1.1 encryption algorithms that are enabled" can be one of:

AES-256-GCM/AES-256-CCM/AES-128-GCM/AES-128-CCM should be enabled
7 == 0111
AES-256-CCM/AES-128-GCM/AES-128-CCM should be enabled
AES-128-GCM/AES-128-CCM should be enabled
AES-128-CCM should be enabled

"Bitmap of SMB 3.1.1 compressions algorithms that are enabled" can be any combination of (set to 0 to disable compression):

PatternV1 should be enabled (only valid if chained compressions are supported)
4 == 0100
LZ77+Huffman should be enabled.
LZ77 should be enabled
LZNT1 should be enabled

/etc/nsmb.conf
The global configuration file.
~/Library/Preferences/nsmb.conf
The user's configuration file, conflicts will be overwritten by the global file.

What follows is a sample configuration file which may, or may not match your environment:

# Configuration file for example.com
[default]
minauth=ntlmv2
streams=yes
soft=yes
notify_off=yes
comp_exclude_list=foo,bar
[WIN11]
addr=windows11.apple.com

All lines which begin with the ‘#’ character are comments and will not be parsed. The “default” section specifies that only Kerberos and NTLMv2 authentication should be attempted; NTLM authentication should not be attempted if NTLMv2 authentication fails, and plain-text authentication should not be attempted if the server doesn't support encrypted passwords.

smbutil(1), mount_smbfs(8)

This manual page was originally written by Sergey Osokin ⟨osa@FreeBSD.org⟩ and Tom Rhodes ⟨trhodes@FreeBSD.org⟩.

June 30, 2003 Mac OS X 12