diff --git a/build.cfg b/build.cfg
index 2f294b5..ee4e9cc 100755
--- a/build.cfg
+++ b/build.cfg
@@ -3,6 +3,7 @@ modules/debug/log.lua
 modules/base/header.lua
 modules/base/component.lua
 modules/lib/fs.lua
+modules/util/logflush.lua
 modules/lib/buffer.lua
 modules/lib/io.lua
 modules/drivers/vt52.lua
diff --git a/modules/lib/relib.lua b/modules/lib/relib.lua
index bec6d93..16022f2 100644
--- a/modules/lib/relib.lua
+++ b/modules/lib/relib.lua
@@ -11,7 +11,7 @@ function relib.encode(p)
 end
 function relib.decode(dat)
  if type(dat) == "string" then
-  if dat:len() > 7 then
+  if dat:len() >= 7 then
    local p = {}
    p.port = tonumber(string.format("%x%x",string.byte(dat:sub(1,1)),string.byte(dat:sub(2,2))),16)
    p.pid = dat:sub(3,5)
diff --git a/modules/net/copper.lua b/modules/net/copper.lua
index 92de0ce..8d91483 100644
--- a/modules/net/copper.lua
+++ b/modules/net/copper.lua
@@ -9,9 +9,10 @@ function net.send(id,po,msg) -- id, port, message
  end
 end
 if cdlib and relib then
-spawn("copperd",function() print(pcall(function ()
+spawn("copperd",function() print(xpcall(function ()
  local pt = {}
  local ps = {}
+ local fcache = {}
  for a,t in component.list("modem") do
   table.insert(net.tm,component.proxy(a))
   component.proxy(a).open(net.np)
@@ -35,29 +36,41 @@ spawn("copperd",function() print(pcall(function ()
    ps[p.pid] = p
   elseif ev[1] == "modem_message" and ev[4] == net.np and ev[6] == "copper" then
    local hops,src,dst,data = cdlib.decode(ev[7])
-   if not pt[ev[7]:sub(2)] then
-    pt[ev[7]:sub(2)] = os.time()
-    if dst == net.id then
-     event.push("net_rmsg",src,data)
-     local pd = relib.decode(data)
-     if pd then
-      if pd.port and pd.pid and pd.at and pd.pt and pd.msg then
-       if pd.pt == 1 then
-        event.push("net_msg",src,pd.port,pd.msg)
-        pd.pt = 2
-        pd.nid = src
-        pd.lt = 0
-        pd.msg = ""
-        ps[pd.pid] = pd
-       elseif pd.pt == 2 then
-        ps[pd.pid] = nil
+   if hops and src and dst and data then
+    if not fcache[src] then
+     log("fcache["..tostring(src).."] = "..tostring(ev[3]))
+     fcache[src] = {ev[2],ev[3],os.time()}
+    end
+    if not pt[ev[7]:sub(2)] then
+     pt[ev[7]:sub(2)] = os.time()
+     if dst == net.id then
+      event.push("net_rmsg",src,data)
+      local pd = relib.decode(data)
+      if pd then
+       if pd.port and pd.pid and pd.at and pd.pt then
+        if pd.pt == 1 then
+         event.push("net_msg",src,pd.port,pd.msg)
+         pd.pt = 2
+         pd.nid = src
+         pd.lt = 0
+         pd.msg = ""
+         ps[pd.pid] = pd
+	 log("[copperd] sent ack to "..src)
+        elseif pd.pt == 2 then
+	 log("[copperd] received ack from "..src.." for "..pd.pid)
+         ps[pd.pid] = nil
+        end
        end
       end
-     end
-    else
-     if hops < 255 then
-      for k,v in ipairs(net.tm) do
-       v.broadcast(net.np,"copper",cdlib.encode(hops+1,src,dst,data))
+     else
+      if hops < 255 then
+       if fcache[dst] and _G.LKR_CACHE then
+        component.invoke(fcache[dst][1],"send",fcache[dst][2],net.np,"copper",cdlib.encode(hops+1,src,dst,data))
+       else
+        for k,v in ipairs(net.tm) do
+         v.broadcast(net.np,"copper",cdlib.encode(hops+1,src,dst,data))
+        end
+       end
       end
      end
     end
@@ -65,8 +78,15 @@ spawn("copperd",function() print(pcall(function ()
   end
   for k,v in pairs(ps) do
    if v.lt < os.time()-1 then
-    for l,m in ipairs(net.tm) do
-     m.broadcast(net.np,"copper",cdlib.encode(0,net.id,v.nid,relib.encode(v)))
+    if fcache[v.nid] and _G.LKR_CACHE then
+     local lma = fcache[v.nid][1]
+     local rma = fcache[v.nid][2]
+     print(lma,rma)
+     component.invoke(lma,"send",rma,net.np,"copper",cdlib.encode(0,net.id,v.nid,relib.encode(v)))
+    else
+     for l,m in ipairs(net.tm) do
+      m.broadcast(net.np,"copper",cdlib.encode(0,net.id,v.nid,relib.encode(v)))
+     end
     end
     v.at = v.at + 1
     v.lt = os.time()
diff --git a/modules/util/logflush.lua b/modules/util/logflush.lua
new file mode 100644
index 0000000..ccfdb69
--- /dev/null
+++ b/modules/util/logflush.lua
@@ -0,0 +1,16 @@
+spawn("logflushd",function()
+ local lt = os.time()
+ while true do
+  if os.time() > lt + 60 and Log:len() > 0 then
+   local f = fs.open("/tmp/sys.log","ab")
+   if f then
+    for i = 1, #Log, 1024 do
+    fs.write(f,Log:sub(i,i+1023))
+    end
+    fs.close(f)
+    Log = ""
+   end
+  end
+  coroutine.yield()
+ end
+end)