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T-024: Vulnerability in Server Message Block (SMB)
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NSMB.CONF(5) BSD File Formats Manual NSMB.CONF(5) NAME
nsmb.conf -- configuration file for SMB requests DESCRIPTION
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: A) [default] B) [SERVER] C) [SERVER:SHARE] Possible keywords may include: Keyword 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 + + - normal How to use SMB TCP/UDP ports streams + + + yes Use NTFS Streams if server supported soft + + + Make the mount 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_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 The minimum authentication level can be one of: kerberos Kerberos - NTLMv2, NTLM, LM, and plain-text password authentication are not attempted. ntlmv2 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 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 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 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: normal Attempt to connect via port 445. If that is unsuccessful, try to connect via NetBIOS. netbios_only Do not attempt to connect via port 445. no_netbios 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: 7 Signing required for SMB 1/2/3. 6 Signing required for SMB 2/3. 4 Signing required for SMB 3. FILES
/etc/nsmb.conf The global configuration file. ~/Library/Preferences/nsmb.conf The user's configuration file, conflicts will be overwritten by the global file. EXAMPLES
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 [WINXP] addr=windowsXP.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 authen- tication should not be attempted if the server doesn't support encrypted passwords. SEE ALSO
smbutil(1), mount_smbfs(8) AUTHORS
This manual page was originally written by Sergey Osokin <osa@FreeBSD.org> and Tom Rhodes <trhodes@FreeBSD.org>. BSD
June 30, 2003 BSD
