Modern server operating systems are tuned for high network performance in the majority of situations; when you set socket options you are overriding those settings. Linux in particular has an auto-tuning mechanism for buffer sizes that will be disabled if you specify a socket buffer size. This can potentially cripple your TCP/IP stack. Getting the socket options correct can make a big difference to your performance, but getting them wrong can degrade it by just as much. As with any other low level setting, if you must make changes to it, make small changes and test the effect before making any large changes. This option allows you to set socket options to be used when talking with the client. Socket options are controls on the networking layer of the operating systems which allow the connection to be tuned. This option will typically be used to tune your Samba server for optimal performance for your local network. There is no way that Samba can know what the optimal parameters are for your net, so you must experiment and choose them yourself. We strongly suggest you read the appropriate documentation for your operating system first (perhaps man setsockopt will help). You may find that on some systems Samba will say "Unknown socket option" when you supply an option. This means you either incorrectly typed it or you need to add an include file to includes.h for your OS. If the latter is the case please send the patch to samba-technical@lists.samba.org. Any of the supported socket options may be combined in any way you like, as long as your OS allows it. This is the list of socket options currently settable using this option: SO_KEEPALIVE SO_REUSEADDR SO_BROADCAST TCP_NODELAY TCP_KEEPCNT * TCP_KEEPIDLE * TCP_KEEPINTVL * IPTOS_LOWDELAY IPTOS_THROUGHPUT SO_REUSEPORT SO_SNDBUF * SO_RCVBUF * SO_SNDLOWAT * SO_RCVLOWAT * SO_SNDTIMEO * SO_RCVTIMEO * TCP_FASTACK * TCP_QUICKACK TCP_NODELAYACK TCP_KEEPALIVE_THRESHOLD * TCP_KEEPALIVE_ABORT_THRESHOLD * TCP_DEFER_ACCEPT * TCP_USER_TIMEOUT * Those marked with a '*' take an integer argument. The others can optionally take a 1 or 0 argument to enable or disable the option, by default they will be enabled if you don't specify 1 or 0. To specify an argument use the syntax SOME_OPTION = VALUE for example SO_SNDBUF = 8192. Note that you must not have any spaces before or after the = sign. If you are on a local network then a sensible option might be: socket options = IPTOS_LOWDELAY If you have a local network then you could try: socket options = IPTOS_LOWDELAY TCP_NODELAY If you are on a wide area network then perhaps try setting IPTOS_THROUGHPUT. Note that several of the options may cause your Samba server to fail completely. Use these options with caution! TCP_NODELAY IPTOS_LOWDELAY