Using NASM and TCP Sockets - sockets

Question

I am trying to teach myself some NASM x86 assembly using some Unix system calls. I am trying to create a simple TCP server and I have the code working up until the send() command. I can connect via telnet but I get a segfault once my code reaches the point where it tries to send a response to the client.
This is the segment of code that is producing a segfault:
; push on to stack for send
push dword 0
push dword [start_len]
push dword [start]
push dword [socket]
; send something back
; THIS IS WHERE THE SEGFAULT OCCURS
mov eax,102
mov ebx,9 ; send is 9
mov ecx,esp
int 80h
Here is the full source code if anyone wants to look at it. Any help would be greatly appreciated!
; constants go here
section .data
start: db 'Starting Socket...',0
start_len: equ $-start
; variables go here
section .bss
socket: resd 1 ; store the fd for the socket
socket_address: resd 2 ; socket address
; starttttt
section .text
global _start
open_socket:
; print we are starting
mov eax,4
mov ebx,1
mov ecx,start
mov edx,start_len
int 80h
; push values to stack to make call
; values go in in opposite order, so when they are popped
; it is the correct order
; below is for a tcp socket
push dword 6
push dword 1
push dword 2
; make call to open socket
mov eax,102 ; 102 is the call to open socket
mov ebx,1 ; sub call, socket()
mov ecx,esp
int 80h
; store the file descriptor for the socket
mov dword[socket],eax
; this is the socket address to bind to
push dword 0x00000000 ; localhost (127.0.0.1)
push dword 0x2823 ; port 9000
push word 2 ; AF_INET (IPv4)
mov [socket_address],esp ; move to our socket address variable
; setup parameters for bind call bind(socket, socket_address, 16)
push dword 16
push dword [socket_address]
push dword [socket]
; call subcall for socket to bind
mov eax,102; sys_socket
mov ebx,2 ; subcall 2 = bind()
mov ecx,esp ; push vars from stack to params
int 80h
; setup parameters for listen()
push byte 20
push dword [socket]
; call listen()
mov eax,102 ; socket call
mov ebx,4 ; subcall listen()
mov ecx,esp ; move stack as variables
int 80h
; now we have to accept incoming connections...
; setup the call
push 0
push 0
push dword [socket]
; call accept()
mov eax,102
mov ebx,5
mov ecx,esp
int 80h
; push on to stack for send
push dword 0
push dword [start_len]
push dword [start]
push dword [socket]
; send something back
; THIS IS WHERE THE SEGFAULT OCCURS
mov eax,102
mov ebx,9 ; send is 9
mov ecx,esp
int 80h
; function to exit the program
exit:
mov eax,1
mov ebx,0
int 80h
; main function to be called
_start:
; open it
call open_socket