This option allows you to override the default network interfaces list that Samba will use for browsing, name registration and other NetBIOS over TCP/IP (NBT) traffic. By default Samba will query the kernel for the list of all active interfaces and use any interfaces except 127.0.0.1 that are broadcast capable.
The option takes a list of interface strings. Each string can be in any of the following forms:
a network interface name (such as eth0). This may include shell-like wildcards so eth* will match any interface starting with the substring "eth" an IP address. In this case the netmask is determined from the list of interfaces obtained from the kernel an IP/mask pair. a broadcast/mask pair.
The "mask" parameters can either be a bit length (such as 24 for a C class network) or a full netmask in dotted decimal form.
The "IP" parameters above can either be a full dotted decimal IP address or a hostname which will be looked up via the OS's normal hostname resolution mechanisms.
By default Samba enables all active interfaces that are broadcast capable except the loopback adaptor (IP address 127.0.0.1).
In order to support SMB3 multi-channel configurations, smbd understands some extra parameters which can be appended after the actual interface with this extended syntax (note that the quoting is important in order to handle the ; and , characters):
Known keys are speed, capability, and if_index. Speed is specified in bits per second. Known capabilities are RSS and RDMA. The if_index should be used with care: the values must not coincide with indexes used by the kernel. Note that these options are mainly intended for testing and development rather than for production use. At least on Linux systems, these values should be auto-detected, but the settings can serve as last a resort when autodetection is not working or is not available. The specified values overwrite the auto-detected values.
The first two example below configures three network interfaces corresponding to the eth0 device and IP addresses 192.168.2.10 and 192.168.3.10. The netmasks of the latter two interfaces would be set to 255.255.255.0.
The other examples show how per interface extra parameters can be specified. Notice the possible usage of "," and ";", which makes the double quoting necessary.
Example: eth0 192.168.2.10/24 192.168.3.10/255.255.255.0
Example: eth0, 192.168.2.10/24; 192.168.3.10/255.255.255.0
Example: "lo;speed=1000000000" "eth0;capability=RSS"
Example: "lo;speed=1000000000" , "eth0;capability=RSS"
Example: "eth0;capability=RSS" , "rdma1;capability=RDMA" ; "rdma2;capability=RSS,capability=RDMA"