How to find the socket buffer size of linux

Question

What s the default socket buffer size of linux  Is there any command to see it

User · Accepted Answer

If you want see your buffer size in terminal, you can take a look at:

/proc/sys/net/ipv4/tcp_rmem (for read)
/proc/sys/net/ipv4/tcp_wmem (for write)

They contain three numbers, which are minimum, default and maximum memory size values (in byte), respectively.

User · Answer

Whilst  as has been pointed out  it is possible to see the current default socket buffer sizes in  proc  it is also possible to check them using sysctl  Note  Whilst the name includes ipv4 these sizes also apply to ipv6 sockets - the ipv6 tcp v6 init sock   code just calls the ipv4 tcp init sock   function     sysctl net ipv4 tcp rmem  sysctl net ipv4 tcp wmem   However  the default socket buffers are just set when the sock is initialised but the kernel then dynamically sizes them  unless set using setsockopt   with SO SNDBUF   The actual size of the buffers for currently open sockets may be inspected using the ss command  part of the iproute package   which can also provide a bunch more info on sockets like congestion control parameter etc  E g  To list the currently open TCP  t option  sockets and associated memory  m  information   ss -tm   Here s some example output   State       Recv-Q Send-Q        Local Address Port        Peer Address Port ESTAB       0      0             192 168 56 102 ssh        192 168 56 1 56328 skmem  r0 rb369280 t0 tb87040 f0 w0 o0 bl0 d0    Here s a brief explanation of skmem  socket memory  - for more info you ll need to look at the kernel sources  e g  sock h     r sk rmem alloc rb sk rcvbuf            current receive buffer size t sk wmem alloc tb sk sndbuf            current transmit buffer size f sk forward alloc w sk wmem queued        persistent transmit queue size o sk omem alloc bl sk backlog d sk drops

User · Answer

For getting the buffer size in c c   program the following is the flow  int n  unsigned int m   sizeof n   int fdsocket  fdsocket   socket AF INET SOCK DGRAM IPPROTO UDP      example getsockopt fdsocket SOL SOCKET SO RCVBUF  void    amp n   amp m      now the variable n will have the socket size

User · Answer

Atomic size is 4096 bytes  max size is 65536 bytes  Sendfile uses 16 pipes each of 4096 bytes size  cmd   ioctl fd  FIONREAD   amp buff size

[linux] How to find the socket buffer size of linux

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