Strangeness with Linksys WRT54G

[Bob Willard]

I had a weird problem for a few days on my home LAN, using a
Linksys WRT54G v2 router (v4.20.7 µCode), tied to WAN via
Moto SB 4200 to Comcast.

Symptom 1: Could not send or forward long (>1000 bytes) emails
from Moz v1.7 on wired XP PRO PC: after ~60 Secs, Moz reported
failure to connect to smtp server; but, short (<200 bytes) emails
sent OK. Same problem with Moz v1.7 on wireless XP MC PC, and same
problem with Netscape v7.1 on wired W98 PC. No problem with
WinMail on wireless Vista PC at any message size.

Symptom 2: Could not connect to some websites with either FF v2
or IE v7 from wired XP PRO PC: connections timed out. I think
the common factor was using https instead of http, but I'm not
really sure.

Aside: transfers of up to 1 MB uphill and up to 16MB downhill
via FTP work OK, and at full speed; no sign of errors.

Solution: power down the router for >3 minutes, then power back up.
Note that powering down for >20 seconds (tried twice) was *not*
long enough to clear the problem, but a surprisingly long power-off
period (while I temporarily bypassed the router) did the job.

Weird, huh? Maybe this 3-year old router has Alzheimer's?

--
Cheers, Bob

[Bill Kearney]

> Solution: power down the router for >3 minutes, then power back up.
> Note that powering down for >20 seconds (tried twice) was *not*
> long enough to clear the problem, but a surprisingly long power-off
> period (while I temporarily bypassed the router) did the job.
>
> Weird, huh? Maybe this 3-year old router has Alzheimer's?

Long timeouts like that sound more like there's gear UPSTREAM at the ISP
that has to timeout, not this equipment. Try this, instead of powering it
off, physically DISCONNECT it from the cable modem. Wait that 3 minute
period, reconnect it and see if the "problem" went away. I'm guessing it
will.

That being the case there are other debug steps to consider.

[Bob Willard]

Bill Kearney wrote:
>> Solution: power down the router for >3 minutes, then power back up.
>> Note that powering down for >20 seconds (tried twice) was *not*
>> long enough to clear the problem, but a surprisingly long power-off
>> period (while I temporarily bypassed the router) did the job.
>>
>> Weird, huh? Maybe this 3-year old router has Alzheimer's?
>
>
> Long timeouts like that sound more like there's gear UPSTREAM at the ISP
> that has to timeout, not this equipment. Try this, instead of powering
> it off, physically DISCONNECT it from the cable modem. Wait that 3
> minute period, reconnect it and see if the "problem" went away. I'm
> guessing it will.
>
> That being the case there are other debug steps to consider.

Interesting. I can't tell the diff, since the router was both powered
down and uncabled. And, the problem has gone away (for now).
--
Thanks & Cheers, Bob

[Bill Kearney]

> Interesting. I can't tell the diff, since the router was both powered
> down and uncabled. And, the problem has gone away (for now).

Here's a thought, what other traffic was being routed through it? Is it an
open wifi network? Might've been something else hammering a ton of traffic
through the link and that tripped something on the ISP's side of things.

[Bob Willard]

Bill Kearney wrote:

>> Interesting. I can't tell the diff, since the router was both powered
>> down and uncabled. And, the problem has gone away (for now).
>
>
> Here's a thought, what other traffic was being routed through it? Is it
> an open wifi network? Might've been something else hammering a ton of
> traffic through the link and that tripped something on the ISP's side of
> things.
>

The WiFi segment is secured with WPA, and usually pretty light anyway. The
bulk of my LAN traffic is on the wired side, including a gamer (sometimes 2).
But the traffic wasn't unusually heavy when the router went funny.

I'm holding my breath, to see if the router (or whatever) goes awry again.
This Linksys router is ~3 years old, and the previous router (Linksys) lasted
for ~5 years before the radio front-end died.
--
Cheers, Bob

[Jeff Liebermann]

On Tue, 04 Mar 2008 09:16:12 -0500, Bob Willard
<BobwBSGS@TrashThis.comcast.net> wrote:

>I had a weird problem for a few days on my home LAN, using a
>Linksys WRT54G v2 router (v4.20.7 µCode), tied to WAN via
>Moto SB 4200 to Comcast.

The current firmware version is 4.21.1.
<http://www.linksys.com/servlet/Satellite?c=L_CASupport_C2&childpagename=US%2FLayout&cid=1166859837401&pagename=Linksys%2FCommon%2FVisitorWrapper&lid=3740137314B343&displaypage=download#versiondetail>
There doesn't seem to be anything related to this problem in the
release notes:
<http://www.linksys.com/servlet/Satellite?blobcol=urldata&blobheadername1=Content-Type&blobheadername2=Content-Disposition&blobheadervalue1=text%2Fplain&blobheadervalue2=inline%3B+filename%3Dwrt54g_ver%252C15.txt&blobkey=id&blobtable=MungoBlobs&blobwhere=1193768670586&ssbinary=true&lid=0724537401B97>
but methinks it's worth trying a firmware update anyway.

>Symptom 1: Could not send or forward long (>1000 bytes) emails
>from Moz v1.7 on wired XP PRO PC: after ~60 Secs, Moz reported
>failure to connect to smtp server; but, short (<200 bytes) emails
>sent OK.

That's odd. You can connect to an SMTP server if you append a short
message, but can't with a long message. The problem is that the
initial SMTP connection is made *BEFORE* the message is sent. If it
can't connect, it doesn't matter how long a message follows. Can you
be more specific as to the error message?

>Same problem with Moz v1.7 on wireless XP MC PC, and same
>problem with Netscape v7.1 on wired W98 PC. No problem with
>WinMail on wireless Vista PC at any message size.

weird. Look at the first setup page on the WRT54. What do you have
for the MTU (maximum transfer unit)? For a cable modem, it should be
1500 bytes.
<http://ui.linksys.com/files/WRT54G/v1-v4/4.20.7/>

One possibility is that you have a sick router on the path between you
and your SMTP server. Go unto:
<http://www.elifulkerson.com/projects/mturoute.php>
and grab MTUROUTE.EXE v2.1. Run it and see if you can actually use
1500 bytes.

>Symptom 2: Could not connect to some websites with either FF v2
>or IE v7 from wired XP PRO PC: connections timed out.

Same issue. Run MTUTROUTE pointing it to the web servers with
problems. Compare with a web server that is close to your ISP and
does not go through many other routers and spagetti.

>I think
>the common factor was using https instead of http, but I'm not
>really sure.

It's possible. However, if there are any imparements involving SSL
and encryption, you'll get a very different assortment of nasty error
messages from the browser.

>Aside: transfers of up to 1 MB uphill and up to 16MB downhill
>via FTP work OK, and at full speed; no sign of errors.

Weird 2.0. If it were an Max MTU problem, then it should show up on
the downloads. However, that assumes that the downloads and the
problem web sites go via the same router when leaving your ISP.

>Solution: power down the router for >3 minutes, then power back up.
>Note that powering down for >20 seconds (tried twice) was *not*
>long enough to clear the problem, but a surprisingly long power-off
>period (while I temporarily bypassed the router) did the job.

Smells like a buffer overflow problem in the router. Try the firmware
update.

>Weird, huh? Maybe this 3-year old router has Alzheimer's?

Yeah, it's weird. If you have another router, see if it does the same
thing. That will at least determine if the router is at fault.

--
# Jeff Liebermann 150 Felker St #D Santa Cruz CA 95060
# 831-336-2558 jeffl@comix.santa-cruz.ca.us
# http://802.11junk.com jeffl@cruzio.com
# http://www.LearnByDestroying.com AE6KS

[Bill Kearney]

> I'm holding my breath, to see if the router (or whatever) goes awry again.

And when it does remove the ethernet cable from it first and wait the 3+
minutes. Or longer. You do want to rule out that it's not something being
blocked upstream.

Hmm, here's another suggestion, change the hardware MAC address of the WAN
port. It's buried in the setup pages on the router. This would,
effectively, make the upstream network think a new device had been attached.
This probably won't do anything. It's more likely any upstream filtering
(or whatever) is tied to the IP address more than the MAC. If you change
it make sure to change it back.

If the disconnecting doesn't work, then try powering down the DSL modem for
that same delay. Couldn't hurt to rule it out.

[Bob Willard]

Jeff Liebermann wrote:
> On Tue, 04 Mar 2008 09:16:12 -0500, Bob Willard
> <BobwBSGS@TrashThis.comcast.net> wrote:
>
>
>>I had a weird problem for a few days on my home LAN, using a
>>Linksys WRT54G v2 router (v4.20.7 µCode), tied to WAN via
>>Moto SB 4200 to Comcast.
>
>
> The current firmware version is 4.21.1.
> <http://www.linksys.com/servlet/Satellite?c=L_CASupport_C2&childpagename=US%2FLayout&cid=1166859837401&pagename=Linksys%2FCommon%2FVisitorWrapper&lid=3740137314B343&displaypage=download#versiondetail>
> There doesn't seem to be anything related to this problem in the
> release notes:
> <http://www.linksys.com/servlet/Satellite?blobcol=urldata&blobheadername1=Content-Type&blobheadername2=Content-Disposition&blobheadervalue1=text%2Fplain&blobheadervalue2=inline%3B+filename%3Dwrt54g_ver%252C15.txt&blobkey=id&blobtable=MungoBlobs&blobwhere=1193768670586&ssbinary=true&lid=0724537401B97>
> but methinks it's worth trying a firmware update anyway.
>
>
>>Symptom 1: Could not send or forward long (>1000 bytes) emails
>
>>from Moz v1.7 on wired XP PRO PC: after ~60 Secs, Moz reported
>
>>failure to connect to smtp server; but, short (<200 bytes) emails
>>sent OK.
>
>
> That's odd. You can connect to an SMTP server if you append a short
> message, but can't with a long message. The problem is that the
> initial SMTP connection is made *BEFORE* the message is sent. If it
> can't connect, it doesn't matter how long a message follows. Can you
> be more specific as to the error message?
>
>
>>Same problem with Moz v1.7 on wireless XP MC PC, and same
>>problem with Netscape v7.1 on wired W98 PC. No problem with
>>WinMail on wireless Vista PC at any message size.
>
>
> weird. Look at the first setup page on the WRT54. What do you have
> for the MTU (maximum transfer unit)? For a cable modem, it should be
> 1500 bytes.
> <http://ui.linksys.com/files/WRT54G/v1-v4/4.20.7/>
>
> One possibility is that you have a sick router on the path between you
> and your SMTP server. Go unto:
> <http://www.elifulkerson.com/projects/mturoute.php>
> and grab MTUROUTE.EXE v2.1. Run it and see if you can actually use
> 1500 bytes.
>
>
>>Symptom 2: Could not connect to some websites with either FF v2
>>or IE v7 from wired XP PRO PC: connections timed out.
>
>
> Same issue. Run MTUTROUTE pointing it to the web servers with
> problems. Compare with a web server that is close to your ISP and
> does not go through many other routers and spagetti.
>
>
>>I think
>>the common factor was using https instead of http, but I'm not
>>really sure.
>
>
> It's possible. However, if there are any imparements involving SSL
> and encryption, you'll get a very different assortment of nasty error
> messages from the browser.
>
>
>>Aside: transfers of up to 1 MB uphill and up to 16MB downhill
>>via FTP work OK, and at full speed; no sign of errors.
>
>
> Weird 2.0. If it were an Max MTU problem, then it should show up on
> the downloads. However, that assumes that the downloads and the
> problem web sites go via the same router when leaving your ISP.
>
>
>>Solution: power down the router for >3 minutes, then power back up.
>>Note that powering down for >20 seconds (tried twice) was *not*
>>long enough to clear the problem, but a surprisingly long power-off
>>period (while I temporarily bypassed the router) did the job.
>
>
> Smells like a buffer overflow problem in the router. Try the firmware
> update.
>
>
>>Weird, huh? Maybe this 3-year old router has Alzheimer's?
>
>
> Yeah, it's weird. If you have another router, see if it does the same
> thing. That will at least determine if the router is at fault.
>

It is not MTU; I've used MTU=1500 on the router and all PCs for years.
And I only have one router in my LAN (I've stretched the 4-port LAN by
using a hub to connect in 3 PCs that use the WAN sparingly).

Yeah, a buffer overflow fits. If it comes back, I may try to update the
firmware, even though the firmware notes did not say anything about
fixing this kind of problem.
--
Thanks & Cheers, Bob