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Diffstat (limited to 'docs/textdocs')
| -rw-r--r-- | docs/textdocs/BROWSING.txt | 394 |
1 files changed, 368 insertions, 26 deletions
diff --git a/docs/textdocs/BROWSING.txt b/docs/textdocs/BROWSING.txt index cee09813a7..19e7888477 100644 --- a/docs/textdocs/BROWSING.txt +++ b/docs/textdocs/BROWSING.txt @@ -15,6 +15,9 @@ wide area network server list. In order for browse clients to resolve the names they may find in this list, it is recommended that both samba and your clients use a WINS server +Note that you should NOT set Samba to be the domain master for a +workgroup that has the same name as an NT Domain. + [Note that nmbd can be configured as a WINS server, but it is not necessary to specifically use samba as your WINS server. NTAS can be configured as your WINS server. In a mixed NT server and @@ -56,6 +59,368 @@ The other big problem people have is that their broadcast address, netmask or IP address is wrong (specified with the "interfaces" option in smb.conf) +BROWSING ACROSS SUBNETS +======================= + +With the release of Samba 1.9.17(alpha1 and above) Samba has been +updated to enable it to support the replication of browse lists +across subnet boundaries. New code and options have been added to +achieve this. This section describes how to set this feature up +in different settings. + +To see browse lists that span TCP/IP subnets (ie. networks separated +by routers that don't pass broadcast traffic) you must set up at least +one WINS server. The WINS server acts as a DNS for NetBIOS names, allowing +NetBIOS name to IP address translation to be done by doing a direct +query of the WINS server. This is done via a directed UDP packet on +port 137 to the WINS server machine. The reason for a WINS server is +that by default, all NetBIOS name to IP address translation is done +by broadcasts from the querying machine. This means that machines +on one subnet will not be able to resolve the names of machines on +another subnet without using a WINS server. + +Remember, for browsing across subnets to work correctly, all machines, +be they Windows 95, Windows NT, or Samba servers must have the IP address +of a WINS server given to them by a DHCP server, or by manual configuration +(for Win95 and WinNT, this is in the TCP/IP Properties, under Network +settings) for Samba this is in the smb.conf file. + +How does cross subnet browsing work ? +===================================== + +Cross subnet browsing is a complicated dance, containing multiple +moving parts. It has taken Microsoft several years to get the code +that achieves this correct, and Samba lags behind in some areas. +However, with the 1.9.17 release, Samba is capable of cross subnet +browsing when configured correctly. + +Consider a network set up as follows : + + (DMB) + N1_A N1_B N1_C N1_D N1_E + | | | | | + ------------------------------------------------------- + | subnet 1 | + +---+ +---+ + |R1 | Router 1 Router 2 |R2 | + +---+ +---+ + | | + | subnet 2 subnet 3 | + -------------------------- ------------------------------------ + | | | | | | | | + N2_A N2_B N2_C N2_D N3_A N3_B N3_C N3_D + (WINS) + +Consisting of 3 subnets (1, 2, 3) conneted by two routers +(R1, R2) - these do not pass broadcasts. Subnet 1 has 5 machines +on it, subnet 2 has 4 machines, subnet 3 has 4 machines. Assume +for the moment that all these machines are configured to be in the +same workgroup (for simplicities sake). Machine N1_C on subnet 1 +is configured as Domain Master Browser (ie. it will collate the +browse lists for the workgroup). Machine N2_D is configured as +WINS server and all the other machines are configured to register +their NetBIOS names with it. + +As all these machines are booted up, elections for master browsers +will take place on each of the three subnets. Assume that machine +N1_C wins on subnet 1, N2_B wins on subnet 2, and N3_D wins on +subnet 3 - these machines are known as local master browsers for +their particular subnet. N1_C has an advantage in winning as the +local master browser on subnet 1 as it is set up as Domain Master +Browser. + +On each of the three networks, machines that are configured to +offer sharing services will broadcast that they are offering +these services. The local master browser on each subnet will +receive these broadcasts and keep a record of the fact that +the machine is offering a service. This list of records is +the basis of the browse list. For this case, assume that +all the machines are configured to offer services so all machines +will be on the browse list. + +For each network, the local master browser on that network is +considered 'authoritative' for all the names it receives via +local broadcast. This is because a machine seen by the local +master browser via a local broadcast must be on the same +network as the local master browser and thus is a 'trusted' +and 'verifiable' resource. Machines on other networks that +the local master browsers learn about when collating their +browse lists have not been directly seen - these records are +called 'non-authoritative'. + +At this point the browse lists look as follows (these are +the machines you would see in your network neighborhood if +you looked in it on a particular network right now). + +Subnet Browse Master List +------ ------------- ---- +Subnet1 N1_C N1_A, N1_B, N1_C, N1_D, N1_E + +Subnet2 N2_B N2_A, N2_B, N2_C, N2_D + +Subnet3 N3_D N3_A, N3_B, N3_C, N3_D + +Note that at this point all the subnets are separate, no +machine is seen across any of the subnets. + +Now examine subnet 2. As soon as N2_B has become the local +master browser it looks for a Domain master browser to synchronize +its browse list with. It does this by querying the WINS server +(N2_D) for the IP address associated with the NetBIOS name +WORKGROUP<1b>. This name was registerd by the Domain master +browser (N1_C) with the WINS server as soon as it was booted. + +Once N2_B knows the address of the Domain master browser it +tells it that is the local master browser for subnet 2 by +sending a MasterAnnouncement packet as a UDP port 138 packet. +It then synchronizes with it by doing a NetServerEnum2 call. This +tells the Domain Master Browser to send it all the server +names it knows about. Once the domain master browser receives +the MasterAnnouncement packet it schedules a synchronization +request to the sender of that packet. After both synchronizations +are done the browse lists look like : + +Subnet Browse Master List +------ ------------- ---- +Subnet1 N1_C N1_A, N1_B, N1_C, N1_D, N1_E, + N2_A(*), N2_B(*), N2_C(*), N2_D(*) + +Subnet2 N2_B N2_A, N2_B, N2_C, N2_D + N1_A(*), N1_B(*), N1_C(*), N1_D(*), N1_E(*) + +Subnet3 N3_D N3_A, N3_B, N3_C, N3_D + +Servers with a (*) after them are non-authoritative names. + +At this point users looking in their network neighborhood on +subnets 1 or 2 will see all the servers on both, users on +subnet 3 will still only see the servers on their own subnet. + +The same sequence of events that occured for N2_B now occurs +for the local master browser on subnet 3 (N3_D). When it +synchronizes browse lists with the domain master browser (N1_A) +it gets both the server entries on subnet 1, and those on +subnet 2. After N3_D has synchronized with N1_C and vica-versa +the browse lists look like. + +Subnet Browse Master List +------ ------------- ---- +Subnet1 N1_C N1_A, N1_B, N1_C, N1_D, N1_E, + N2_A(*), N2_B(*), N2_C(*), N2_D(*), + N3_A(*), N3_B(*), N3_C(*), N3_D(*) + +Subnet2 N2_B N2_A, N2_B, N2_C, N2_D + N1_A(*), N1_B(*), N1_C(*), N1_D(*), N1_E(*) + +Subnet3 N3_D N3_A, N3_B, N3_C, N3_D + N1_A(*), N1_B(*), N1_C(*), N1_D(*), N1_E(*), + N2_A(*), N2_B(*), N2_C(*), N2_D(*) + +Servers with a (*) after them are non-authoritative names. + +At this point users looking in their network neighborhood on +subnets 1 or 3 will see all the servers on all sunbets, users on +subnet 2 will still only see the servers on subnets 1 and 2, but not 3. + +Finally, the local master browser for subnet 2 (N2_B) will sync again +with the domain master browser (N1_C) and will recieve the missing +server entries. Finally - and as a steady state (if no machines +are removed or shut off) the browse lists will look like : + +Subnet Browse Master List +------ ------------- ---- +Subnet1 N1_C N1_A, N1_B, N1_C, N1_D, N1_E, + N2_A(*), N2_B(*), N2_C(*), N2_D(*), + N3_A(*), N3_B(*), N3_C(*), N3_D(*) + +Subnet2 N2_B N2_A, N2_B, N2_C, N2_D + N1_A(*), N1_B(*), N1_C(*), N1_D(*), N1_E(*) + N3_A(*), N3_B(*), N3_C(*), N3_D(*) + +Subnet3 N3_D N3_A, N3_B, N3_C, N3_D + N1_A(*), N1_B(*), N1_C(*), N1_D(*), N1_E(*), + N2_A(*), N2_B(*), N2_C(*), N2_D(*) + +Servers with a (*) after them are non-authoritative names. + +Synchronizations between the domain master browser and local +master browsers will continue to occur, but this should be a +steady state situation. + +If either router R1 or R2 fails the following will occur: + +1) Names of computers on each side of the inaccessible network fragments +will be maintained for as long as 36 minutes, in the network neighbourhood +lists. + +2) Attempts to connect to these inaccessible computers will fail, but the +names will not be removed from the network neighbourhood lists. + +3) If one of the fragments is cut off from the WINS server, it will only +be able to access servers on its local subnet, by using subnet-isolated +broadcast NetBIOS name resolution. The effects are similar to that of +losing access to a DNS server. + +Setting up a WINS server +======================== + +Either a Samba machine or a Windows NT Server machine may be set up +as a WINS server. To set a Samba machine to be a WINS server you must +add the following option to the smb.conf file on the selected machine : +in the [globals] section add the line + + wins support = yes + +Versions of Samba previous to 1.9.17 had this parameter default to +yes. If you have any older versions of Samba on your network it is +strongly suggested you upgrade to 1.9.17 or above, or at the very +least set the parameter to 'no' on all these machines. + +Machines with "wins support = yes" will keep a list of all NetBIOS +names registered with them, acting as a DNS for NetBIOS names. + +To set up a Windows NT Server as a WINS server you need to set up +the WINS service - see your NT documentation for details. Note that +Windows NT WINS Servers can replicate to each other, allowing more +than one to be set up in a complex subnet environment. As Microsoft +refuse to document these replication protocols Samba cannot currently +participate in these replications. It is possible in the future that +a Samba->Samba WINS replication protocol may be defined, in which +case more than one Samba machine could be set up as a WINS server +but currently only one Samba server should have the "wins support = yes" +parameter set. + +After the WINS server has been configured you must ensure that all +machines participating on the network are configured with the address +of this WINS server. If your WINS server is a Samba machine, fill in +the Samba machine IP address in the "Primary WINS Server" field of +the "Control Panel->Network->Protocols->TCP->WINS Server" dialogs +in Windows 95 or Windows NT. To tell a Samba server the IP address +of the WINS server add the following line to the [global] section of +all smb.conf files : + + wins server = <name or IP address> + +where <name or IP address> is either the DNS name of the WINS server +machine or it's IP address. + +Note that this line MUST NOT BE SET in the smb.conf file of the Samba +server acting as the WINS server itself. If you set both the +"wins support = yes" option and the "wins server = <name>" option then +nmbd will fail to start. + +There are two possible scenarios for setting up cross subnet browsing. +The first details setting up cross subnet browsing on a network containing +Windows 95, Samba and Windows NT machines that are not configured as +part of a Windows NT Domain. The second details setting up cross subnet +browsing on networks that contain NT Domains. + +Setting up Browsing in a WORKGROUP +================================== + +To set up cross subnet browsing on a network containing machines +in up to be in a WORKGROUP, not an NT Domain you need to set up one +Samba server to be the Domain Master Browser (note that this is *NOT* +the same as a Primary Domain Controller, although in an NT Domain the +same machine plays both roles). The role of a Domain master browser is +to collate the browse lists from local master browsers on all the +subnets that have a machine participating in the workgroup. Without +one machine configured as a domain master browser each subnet would +be an isolated workgroup, unable to see any machines on any other +subnet. It is the presense of a domain master browser that makes +cross subnet browsing possible for a workgroup. + +In an WORKGROUP environment the domain master browser must be a +Samba server, and there must only be one domain master browser per +workgroup name (although the same Samba server can act as Domain +master browser for multiple workgroup names). To set up a Samba +server as a domain master browser set the following option in the +[global] section of the smb.conf file : + + domain master = yes + +The domain master browser should also probably be the local master +browser for it's own subnet. In order to achieve this set the following +options in the [global] section of the smb.conf file : + + domain master = yes + local master = yes + preferred master = yes + os level = 65 + +The domain master browser may be the same machine as the WINS +server, if you require. + +Next, you should ensure that each of the subnets contains a +machine that can act as a local master browser for the +workgroup. Any NT machine should be able to do this, as will +Windows 95 machines (although these tend to get rebooted more +often, so it's not such a good idea to use these). To make a +Samba server a local master browser set the following +options in the [global] section of the smb.conf file : + + domain master = no + local master = yes + preferred master = yes + os level = 65 + +Do not do this for more than one Samba server on each subnet, +or they will war with each other over which is to be the local +master browser. + +The "local master" parameter allows Samba to act as a local master +browser. The "preferred master" causes nmbd to force a browser +election on startup and the "os level" parameter sets Samba high +enough so that it should win any browser elections. + +If you have an NT machine on the subnet that you wish to +be the local master browser then you can disable Samba from +becoming a local master browser by setting the following +options in the [global] section of the smb.conf file : + + domain master = no + local master = no + preferred master = no + os level = 0 + +Setting up Browsing in a DOMAIN +=============================== + +If you are adding Samba servers to a Windows NT Domain then +you must not set up a Samba server as a domain master browser. +By default, a Windows NT Primary Domain Controller for a Domain +name is also the Domain master browser for that name, and many +things will break if a Samba server registers the Domain master +browser NetBIOS name (DOMAIN<1B>) with WINS instead of the PDC. + +For subnets other than the one containing the Windows NT PDC +you may set up Samba servers as local master browsers as +described. To make a Samba server a local master browser set +the following options in the [global] section of the smb.conf +file : + + domain master = no + local master = yes + preferred master = yes + os level = 65 + +If you wish to have a Samba server fight the election with machines +on the same subnet you may set the "os level" parameter to lower +levels. By doing this you can tune the order of machines that +will become local master browsers if they are running. For +more details on this see the section "FORCING SAMBA TO BE THE MASTER" +below. + +If you have Windows NT machines that are members of the domain +on all subnets, and you are sure they will always be running then +you can disable Samba from taking part in browser elections and +ever becoming a local master browser by setting following options +in the [global] section of the smb.conf file : + + domain master = no + local master = no + preferred master = no + os level = 0 FORCING SAMBA TO BE THE MASTER ============================== @@ -108,6 +473,9 @@ multiple subnets so that browsing can occur between subnets. You can make samba act as the domain master by setting "domain master = yes" in smb.conf. By default it will not be a domain master. +Note that you should NOT set Samba to be the domain master for a +workgroup that has the same name as an NT Domain. + When samba is the domain master and the master browser it will listen for master announcements (made roughly every twelve minutes) from local master browsers on other subnets and then contact them to synchronise @@ -142,32 +510,6 @@ b) when a client receives a domain-wide browse list, and a user attempts registered its NetBIOS name with the same WINS server, the user will be able to see that host. - -NOTIFYING THE DOMAIN CONTROLLER -=============================== - -If you have a domain controller for the domain which Samba is a part -of then you should add the line "domain controller = address" to -smb.conf. "address" can either be a name available via DNS or a IP -address or a broadcast address. If it is a broadcast address then -Samba will look for a domain controller on that network. - -If you have a domain controller, then you also have a domain master -browser (if your domain controller is Microsoft's NT Advanced Server, -or AT&T's Advanced Server for Unix, or SCO's Advanced File and Print -Server). - -It will therefore be unnecessary for you to make samba a domain master, -and the parameter "domain master" should be set to 'no', and the -parameter "os level" should be set to a value between 0 and 32. -This will ensure that the domain controller will become your domain -master browser, and it only becomes a local master browser for its -subnet. - -When Samba is the local master browser it will regularly contact the -"domain controller" to synchronise browse lists. - - NOTE ABOUT BROADCAST ADDRESSES ============================== |