SMTP Issue - 4.7.0 Timeout waiting for client input.

[GWN21]

I recently upgraded from a WNDR3700 running dd-wrt to the Asus RT-AC66U.

The initial router swap over was no problem. Getting my router setup and configured with all the setting again was not a problem. I decided to use the Asuswrt-Merlin firmware. I started with 3.0.0.4_354.29_Beta, but after about 4 hours I noticed that the router was rebooting every now and then. So I switched to 3.0.0.4_270.26b and did not have any more rebooting issues. (Kids were not saying the network was down during the middle of a online game.)

After getting everything all setup and my DDNS all squared away (Using DynDNS.org). The RT-AC66U seems to be working without any issues... Wireless was great and all seemed to be working.

The ONLY outstanding issue I had was I haven't received any my emails since I run a mail server. But in the past, every time the router rebooting it grabbed a new WAN IP Address, I knew it took about 1 hours for all the backend DNS to update and the MX BackUp I've setup to find me once again, but after sending a few test emails. I still was not receiving any emails.

Looking at my firewall, I could see DynDNS Mailhop was "talking" to my mail server, but no emails.

Looking at the STMP logs I finally noticed this: (2nd to last line it the noted error):

220 mail.XXXXXX.com Microsoft ESMTP MAIL Service ready at Sat, 29 Jun 2013 17:06:17 -0700",
EHLO mail-11-pao.dyndns.com,
250-mail.XXXXXX.com Hello [216.146.32.40],
250-SIZE 20971520,
250-PIPELINING,
250-DSN,
250-ENHANCEDSTATUSCODES,
250-STARTTLS,
250-X-ANONYMOUSTLS,
250-AUTH NTLM,
250-X-EXPS GSSAPI NTLM,
250-8BITMIME,
250-BINARYMIME,
250-CHUNKING,
250-XEXCH50,
250-XRDST,
250 XSHADOW,
MAIL FROM:<GWN21@gmail.com> SIZE=2181,
08D043388BEFB998;2013-06-30T00:06:17.762Z;1,receiving message
RCPT TO:<GWN21@XXXXXX.com> ORCPT=rfc822;GWN21@XXXXXX.com,
DATA,
250 2.1.0 Sender OK,
250 2.1.5 Recipient OK,
354 Start mail input; end with <CRLF>.<CRLF>,
Remote
451 4.7.0 Timeout waiting for client input,
Local


Did a quick Google Search and one of the thing that was said was the Router Black Hole issues. Where the packets never get sent or finish their "conversation". The other was the firewall was dropping the rest of the packets.

Long story short.... I wasn't having issues with the firewall I was using, but took it out of the loop. Problem still exists. I decided to put the original Router in place (Netgear WNDR3700 running dd-wrt (v24-sp2)). Started to receive all the queued emails about an 1 after the switch back.

So my questions. Can I use the RT-AC66U? (I'm sure I can, just need to find the "right" firmware to use). Was thinking to use the stock ASUS firmware and see if the problem happens there or use the ww-drt firmware on the RT-AC66U.

Anyone has any ideas, suggestions? I'm looking thru the Forums to find out if anyone had a similar issue/problem.

Thanks,

GWN21

 

[Pericynthion]

So that log is your internal IIS log (ie shows an external mail server connecting into your local server, which is internal behind the ASUS)?

From the 822 conversation it looks like the data is never sent from the source - or it's being stripped in transit. How are you exposing port 25? Pot forwarding or in a virtual DMZ?

 

[Pericynthion]

(I only ask in case you were using some of the DD-WRT extended features like the SMTP redirect etc)

 

[GWN21]

So that log is your internal IIS log (ie shows an external mail server connecting into your local server, which is internal behind the ASUS)?

Yes, the logs are from the Exchange SMTP Receive Connector, which is behind the ASUS.

From the 822 conversation it looks like the data is never sent from the source - or it's being stripped in transit. How are you exposing port 25? Pot forwarding or in a virtual DMZ?

Using Port Forwarding on the Asus. Port Forwarding Port 25 to the Mail Server on that port.

Same Port Forwarding setup was done on both the "working" dd-wrt and was done on the Asus.

GWN21

 

[Pericynthion]

did you try to prove the black hole theory with the do-not-fragment ping option ping IP_address -f -l 1472 (http://support.microsoft.com/kb/314825/en-us)

By default the MTU is 1500 on the ports on 66U (assuming you dont have jumbo frames enabled on the LAN) but the ping would prove it - depending on what modem you have it connected to though, it may be negotiating something different locally.

Beyond that I would consider fixing the MTU size on the LAN card as per the KB note - because it certainly smells like a black-hole issue somewhere in the chain.

 

[GWN21]

Yes. Looked into that Router Black Hole issue. Saw that in one of the Google Searched items.

I'm a Frontier FiOS user so, MTU is set at 1492. BOTH of the Routers were set to use a MTU of 1492. I never set or had to set the NIC card on the Mail Server. As when I was using the WNDR3700 with dd-wrt it was set to: 1492 and it was working before the router swap and now as I swapped it back in.

The Asus was set to the same 1492 MTU. And was giving me the SMTP Mail problem. The only thing I have not tired was reverting to the Ausus Firmware or uploading ww-drt into this rounter.

I could also try is set MTU to Auto... And let the router figure it out....

Yeah, there is something going on... Just need to figure it out. Last resort... Get Wireshark... But don't really want to go there yet.

 

[Pericynthion]

Sorry - I might have misunderstood, did you say the ASUS is running 1492? By default its 1500 and you can't change it through the UI, however you can check with an ifconfig command. Plagiarizing from an RMerlin post in another forum;

Try running this over telnet and see if it works:

ifconfig eth0 mtu 1492

If it does, you will have to either re-run that command every time you reboot your router, or switch to my firmware and insert it in the wan-start script.

If you have to resort to DD-WRT there's nothing different about this vs the 3700 (in fact thats exactly what I used to run prior to the 66U) - although I settled on RMerlins build due to the more rapid development cycles. (I dont use the word 'hero' often but in the case of RMerlin.. )

I'd certainly be interested in finding the root cause of this, so feel free to PM anything you want an eye casting over (wireshark logs etc)

 

[GWN21]

Ok... I should also say that I'm running PPPoE as a WAN Connection Type. Usually PPPoE optimal MTU Size is 1492. As I'm not running my Asus Router right now. I can't look. I know in the dd-wrt there is a MTU size setting. You can set it to Auto, where the Router will find the optimal value, or you can manually set it also. If I recall. I think the default Asus firmware has a setting for MTU and MRU, because I remember WOW I never seen a router that had a MRU setting. But I need to re-verify this.

Or.... Hey! anyone out there can you verify this?

I might take you up on the Wireshark logs. It's been quite a while since I've played with it, it was called Ethereal back then.

Okay, back to the MTU Setting. So are you saying that you can not set the MTU size in the UI? I would hope that's not a BUG. As many of my friends have FiOS and it uses PPPoE. And usually we set MTU to Auto or Manually to 1492. Now, I'm going to really need to kick the kids off of there online gaming to do some testing.

Now I'm too really wanting to know what is going on with my new Asus RT-AC66U and my Exchange Server.....

THANKS, Pericynthion!

 

[Pericynthion]

Yep - you're right, if you switch the connection to PPPoE then you DO get an additional MTU and MRU option. You didnt imagine it

I didn't realise you were on the PPPOE setup, so the MTU you define should set it but I would still ssh or run the cmd on the router to verify it against the eth0 with an ipconfig.

If you have the DF flag set, then I think you'll see the incoming packets with 1492 will get passed to the Exch server fine, but I'm not sure if the ACK will go back in a standard 1500 MTU LAN size frame, and then get dropped (because of the DF flag). The 2821/2822 is a 2-way conversation, so thats why I was thinking the LAN card may need fixing at a static size, because I'm not sure if the MTU discovery will traverse the modem/firewall config either or how they will be handled via NAT.

It may be that the established conversations are handled slightly differently in the DD-WRT implementation, or that this is just a 'feature' of the firewall setup.

I'll be honest the ASUS logging is woefully inadequate at this kind of low-level L2/L3 detail, and I got a lot more info from my OpenWRT/DD-WRT based 3700.

 

[GWN21]

So last night I had some time to start testing and see what's going on with my RT-AC66U. I reimaged the unit back to the Factory Firmware 3.0.0.4.354. I used the Asus Firmware Restoration Utility App.

One of the things that I noticed is that while I was running thru the configuration, the router rebooted on me twice in a approx. 40 minute period. When I went to the System Logs > General Logs screen I notice the uptime was @ 1 minute and 40 seconds.

I completed the configuration of the router at 11:30pm and then waited for the Dynamic DNS to update and my MX BackUp to start resenting emails. Figured I'll look in the morning.

Well this morning. Looked at the SMTP Logs and didn't see any updated logs on the SMTPReceive logs. Hmmm. Logged into the router and looked at the System Logs > General Logs and notice that the router had a uptime of 12 minutes.

Great... So it looks like my router has been rebooting it's self all night and the MX BackUp never had enough time at a "stable" enough IP address to send me mail.

So now my questions is did I get a problematic router that I now need to RMA. Sigh....

Don't know if I need to re-firmware the unit again. I know when I was using Asuswrt-Merlin's Beta RT-AC66U-3.0.0.4_354.29-BETA1 firmware I was having the same rebooting issue, about every 20-30 minutes. That's when I changed to the RT-AC66U_3.0.0.4_270.26b and I didn't have any issues with it. So do I reimage to 3.0.0.4.270 and try again or just RMA the unit for a new one?

Thanks,

GWN21


Update: I've installed the Factory Firmware 3.0.0.4.207 on the router... Testing it again.

 

[Pericynthion]

I've had a similar problem on my router with the beta firmware - if I Airplay from my iPad to the AppleTV it works for about an hour , fills the logs up with wireless radio debug and then reboots itself.

If its going every 10 mins or so, might be worth just watching the log for some type of trigger event / log or even better pushing the info to an external syslog.

 

[GWN21]

Well, with the Factory Firmware 3.0.0.4.207 installed. I was up and running for 8 Hours, without any reboots. But no mail being received and I was not getting any SMTP Logs. (So no outside connections from the DynDNS BackUp MX Service.) Looking at the Firewall, I didn't even get an SMTP traffic.

This is really starting to make me think. I've put the OLD WNDR3700 back in place and will see if mail starts up again. Looking at the firewall I didn't see any SMTP Traffic then by test SMTP traffic. Don't know why the BackUp MX was not sending.

Look like I'll try dd-wrt and see how that goes as that what I'm using on the WNDR3700.

NEVER had "THIS" much trouble with a new router....

GWN21

 

[GWN21]

Ok... That was a fun 4th of July. So I've been testing my Asus RT-AC66U Router. I was having issues with receiving SMTP Port 25 Traffic, with Asus's Firmware and Asuswrt-Merlin's firmware.

Long story short. I decided to load dd-wrt on it and TaDa. Everything is working again. I was originally using dd-wrt on my WNDR3700, so looks like I'm now using dd-wrt on my new Asus RT-AC66U.

Guess, when I no longer need my Exchange Server I can use the stock or Merlin firmware. If I had some more time, I'll continue some tests, but as the kids play on the computers and the wife is on the Internet, it's hard to bring down the Internet connection.

I'll see how dd-wrt is on the RT-AC66U. Had to do some quick read up.. But we'll see how it goes.

Thanks for you help Pericynthion! Much appreciate it.

GWN21

 

[Pericynthion]

Anytime - glad to be of help (or at least offering )

Just one quick question, did you reconfigure DD-WRT from scratch or did you restore your old router config? Just curious if this is an aspect of the core DD-WRT vs ASUS code, or whether there is an option enabled/disabled.

 

[GWN21]

Since it was a new system (I went from NetGear to Asus) I figured I reconfigure it all from scratch. Plus I didn't "complicated" it. It had some DDNS Host information and my port-forwarding settings. Simple, less than 5 minutes of reconfiguration tasks.

Plus, it got me to read some of the other stuff dd-wrt can do. Was looking at some DNSMasq settings, so I can access my domain that I use while I'm "connected" to my inside wireless. I can NOW say I'm actually utilizing dd-wrt.

Just curious if this is an aspect of the core DD-WRT vs ASUS code, or whether there is an option enabled/disabled.

I was thinking the same thing, there "must" be a setting that I'm not setting right, but all the other Ports that I'm using 443, 80, 8080 81, 9987 are all working? Just having issues with 25. Plus I can Telnet to 25 and send email manually. Maybe it's my BackUp MX Service. Go Figure.

I'll be testing Exchange 2013, so I may try Merlin's firmware again. I'll let you know if I do.

But dd-wrt is working without any issues. Keeping watch....

GWN21