opc conntrack
netbios port 445,139(smb)
opc port 153
The registration of the opc service requires administrator privileges
opc (DCE (distributed computing environment) /RPC ) package format:
| version | minor | packet type | packet flag |
nf_netfilter_helper:
The hook of the nat module will run when nat is configured, the main work
1: mangle of ip package
2: Provide expectfn hook, which is called when expect ct is triggered
It should be to complete the preparation for the transfer to the source and the transfer to the destination. This function must call nf_nat_setup_info () at the end, which is also the same in the NAT table.
There is a standard function to call: nf_nat_follow_master() , which means to use the same nat method as the master.