nfct-events

#!/usr/bin/env lua5.1
--[[
Print events from netfilter's conntrack subsystem.

Unlike the conntrack utility's -E mode, it can print events from conntrack and
expect at the same time.
]]

require"nfct"

io.stdout:setvbuf"line"

arg[1] = arg[1] or "both"
arg[2] = arg[2] or "all"

cthandle = assert(nfct.open(unpack(arg)))

function cbct(cttype, ct)
    print("ct", nfct.tostring(ct, cttype))
end

function cbexp(cttype, exp)
    print("exp", nfct.exp_tostring(exp, cttype))
end

register = {
    both = function()
        register.conntrack()
        register.expect()
    end,
    conntrack = function()
        assert(nfct.ct_callback_register(cthandle, cbct))
    end,
    expect = function()
        assert(nfct.exp_callback_register(cthandle, cbexp))
    end
}

register[arg[1]]()

assert(nfct.catch(cthandle))