Weird email problem over wireless - Jeff, got yer ears on?

Why me? This has little to do with wireless.

Well, what was changed last? You do keep server logs?

A "few links"? Could you be more specific? Anything inline that would block ports like a router perhaps?

Well, the first step to solving a problem is to blame someone. See if anyone in the office will volunteer. If not, assign the blame to the office masochist (every office has one).

Barf. OE and Ouchlook both trap the original error message, try to interpret it, and give you a bad guess as to what MS thinks it means. If the message came from an Microsoft mail server, you have a chance of figuring it out. If from some other server, it's a crap shoot.

Ok. That means the POP3 server replied with a message similar to "go away".

Digging with Google shows:

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So much for the official line. On to better ways.

  1. Use telnet to get the original error message. Here's a sample POP3 session:

telnet mail.cruzio.com 110

+OK POP3 Ready mail.cruzio.com 0001b54a user jeffl +OK USER jeffl set, mate pass xxxxxxxxxxxxxxxx +OK jeffl has 10 visible messages (0 hidden) in 33288 octets. +OK 10 visible messages (33288 octets) stat +OK 10 33398 list 1 1752 2 1888 3 1753 4 1787 5 1755 6 2430 7 2270 8 2921 9 1459 10 15273 . quit +OK Pop server at bmail.cruzio.com signing off.

  1. I've had chronic problems with MTU discovery issues. Download fping 2.09 from
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    ping your mail server with various size packets. For 1500Byte MTU, the max size is 1472.

C:\>fping 192.168.1.1 -f -s 1472 Pinging 192.168.1.1 with 1472 bytes of data every 1000 ms: Reply[1] from 192.168.1.1: bytes=1472 time=0 ms TTL=150 (trimmed...)

C:\>fping 192.168.1.1 -f -s 1473 Pinging 192.168.1.1 with 1473 bytes of data every 1000 ms: Packet size exceeds MTU and needs to be fragmented but DF set. (trimmed...)

Note that 1472 works, but 1473 generates an error. If you're getting much small MTU's, you may have a connectivity issue.

  1. Check if the mail server is running some kind of firewall (IPChains, IPFilters, etc) and see if it's blocking port 110 for some reason? Same with any intrusion detection system (IDS) or filtering software.

Meanwhile, you're on your own. My truck has an engine problem and it appears that I'm gonna be busy either doing a repair or finding a replacement.

Reply to
Jeff Liebermann
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This started a couple of days ago and it's happening from several computers at several locations. Can't download email over wireless connections, get a server time out error (error message pasted in below). The mail server, SendMail on RedHat 8, is at my office. If I check mail from any of several comps at the office over the LAN, no problems. The wireless connections go through a few links, two ends of a backhaul, then the AP, then the CPE - all smartBridges equipment.

Other than email, all other activities zoom along at a satisfying pace. I don't know of any reason an AP would knock out POP3 stuff, has me puzzled right now. Not even sure it's related to the wireless side of things but it seems more than coincidental.

Suggestions?

Error message from Outlook Express - Your server has unexpectedly terminated the connection. Possible causes for this include server problems, network problems, or a long period of inactivity. Account: 'mail.mydomain.com', Server: 'mail.mydomain.com', Protocol: POP3, Port: 110, Secure(SSL): No, Socket Error: 10053, Error Number: 0x800CCC0F

Reply to
Rôgêr

Well, something has changed. I suggest you interrogate all the usual suspects.

Two access points playing bridge? Can't work. What manner of hardware? What's a "smartbridge"? (My father warned me to stay away from products with superlatives such as super, amazing, magic, miracle, etc. I've added smart, intelligent, advanced, and pro to the list.) Oh...

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nice.

Assumption? How about doing the POP3 test I previous posted. It's easy, painless, and very useful.

OK. It's the backhaul radios. Did some dingbat set the remote management port number to port 110? Instant block if that's what happened. Maybe someone setup a MAC address filter and left out the mail server. See if ping, traceroute, telnet, ftp or some other non-POP3 program works to the mail server.

Bah. Power cycle the backhaul radios and everything plugged into them first. However, I agree that it's "something" in the backhaul. However, I don't have a clue exactly what's busted.

Reply to
Jeff Liebermann

My thoughts at first too, but research shows otherwise.

I've changed socks and undies, nothing about the network or server changed that I'm aware of. Maybe something let the smoke out of some wireless equipment.

No routers between the server and my computer. But there is the backhaul to the tower and then the main access point. The backhaul is two APs configured for that purpose. Has worked just fine for nearly two years.

I guess my wife will have to do.

It's a RedHat 8 server running SendMail. My Linux guy (not me) says the server is working fine. Research says he's right. I associated my home CPE with another access point that is not wireless backhauled and email worked just fine. Switched back to the backhauled AP and email falls down. Everything else buzzes right along.

Reply[1] from 192.168.1.1: bytes=1472 time=20 ms TTL=64 Reply[2] from 192.168.1.1: bytes=1472 time=20 ms TTL=64 Reply[3] from 192.168.1.1: bytes=1472 time=20 ms TTL=64 Reply[4] from 192.168.1.1: bytes=1472 time=20 ms TTL=64 (IP edited to protect the innocent)

Packet size exceeds MTU and needs to be fragmented but DF set. Packet size exceeds MTU and needs to be fragmented but DF set. Packet size exceeds MTU and needs to be fragmented but DF set. Packet size exceeds MTU and needs to be fragmented but DF set.

Nothing changed on the server from a few days before and as I said, my Linux guru says it's okay, logs say everybody should be happy. And unlike me, he knows what he's talking about.

Good luck on the truck, and seriously, thanks for the pointers. I guess it's going to be a matter of swapping out equipment (for me, not you) one piece at a time. That is, unless the guys on the smartBridges list have a suggestion.

Reply to
Rôgêr

I think you need a new truck, judging from the number of repairs you've made to it since last August.

Reply to
dold

Not exactly wireloose. Actually, it's the same problem that's been driving me nuts for the last 9 months. Today, I finally found the problem. The coil windings in the two glow plug relay ($70/ea) became corroded from water incursion and shorted. The solenoids would work, but draw way too much current. The result was plenty of weird and non-obvious symptoms. Eventually the stupid solenoid stuck closed, blew a small relay in the controller box ($8), and fried all 4 glow plugs ($25/ea), which presented an obvious clue. Parts are on order and the demise of my truck is temporarily postponed.

Reply to
Jeff Liebermann

JB Weld, layer of sheet rubber, and two hose clamps. It worked long enough to make it to the repair shop. We ordered a junk gearbox which had a much smaller leak in exactly the same location. Oops. So, I magnifluxed the crack, filed it open, and brazed it shut with my torch. I had to keep it half under a bucket of water to keep the heat from exploding power steering fluid and melting the gaskets. Working fine now.

I drove it home and it wouldn't start the next morning. Clogged diesel fuel filter. Easy fix but took me all day to find it. When the filter started working correctly, the pressure on the backflow hose increased blowing out the hose. I was leaving puddles of diesel in the parking lot before I figured out what was happening. Shoving a piano wire down the hose toward the gas tank removed the blockage.

I've already replaced the water pump so that's not going to blow. I have three alternators that I rebuild as needed. I used much bigger and higher voltage diodes on the last rebuild. It's holding so I don't expect much trouble there. It's a diesel so no smog pump. No A/C. Power steering was recently fixed. Turbo is in good shape. Clutch was replaced when I swapped out the tranny. I did the brakes last year. Not much left to break. Well, the injectors have 150K miles on them, so I guess it's time. I have two sets so it's off to the rebuilders. My only complaint is that I lost a few days of work and that I hate working in the rain with a cold.

One big advantage to fixing trucks to fixing electronics. With the truck we can *SEE* what's leaking, cracked, or smoking. With electronics, we're no better than blind (without test equipment).

Bringing off topic discussions to a new low...

Reply to
Jeff Liebermann

Nah. Once they go over the edge, the little problems all merge and look like one. In August it was the power steering, then it was something that required duct tape (which I presume was not the power steering. I don't think duct tape would hold very long in the face of power steering fluid).

I try to avoid buying more than one set of tires for most of my vehicles. I slipped up a bit on one of them. It's had lots of tires, and all of the accouterments replaced at least once (power steering, water pump, fan clutch, clutch, alternator, U-joints, A/C compressor, smog pump). It has been reduced to garbage hauling and resting quietly in the driveway.

Reply to
dold

I keep the old truck around just as a reminder of what "shade tree mechanics" could do. My newer cars are unrepairable black boxes outside the dealer.

Reply to
dold

Another really useful tool is tcptraceroute if you have a *nix box around. Works well to indicate breakpoint when Telneting to port fails.

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Also Ethereal to see at which point in the conversation the failure is occurring. such as during auth or sending data.

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John

Reply to
John Mason Jr

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