How to modify source code at pfSense

[glkth87]

Hi,

I did test pps(packets per second) by packet generator (pktgen, packETH).

[Topology]

[Host 192.168.1.189] –- LAN --- [F/W (LAN : 192.168.1.183, WAN : 10.1.1.24)] –- WAN --- [Host 10.1.1.25]

But, almost packets are dropped at LAN interface.
When I command "netstat -s", I get result below as.

udp:
        20024058 datagrams received
        0 with incomplete header
        0 with bad data length field
        0 with bad checksum
        20000000 with no checksum
        20000009 dropped due to no socket
        13084 broadcast/multicast datagrams undelivered
        0 dropped due to full socket buffers
        0 not for hashed pcb
        10965 delivered
        11587 datagrams output
        0 times multicast source filter matched

Many site said this is cause of overrun buffer.
So, I want to modify size of buffer. but, I can not find where is source code.

Thank you.