384.7 IPV6 Stateful Generates Logged Errors, Stateless Does Not

[GHammer]

Run it several times in a row....you need to catch dnsmasq before it crashes with the kernel error (I still think there is a dnsmasq bug playing in this)

Ok, I ran it until I got nothing in return.

admin@RT-AC86U-6828:/tmp# killall -SIGHUP dnsmasq
admin@RT-AC86U-6828:/tmp#

 

[GHammer]

Ok, I ran it until I got nothing in return.

admin@RT-AC86U-6828:/tmp# killall -SIGHUP dnsmasq
admin@RT-AC86U-6828:/tmp#

No difference. Same errors logged.

 

[john9527]

Ok, I ran it until I got nothing in return.

Are things working now? Anything different in the syslog?

 

[Sean B.]

killall: dnsmasq: no process killed

Ah, yes, I forgot it starts doing a death loop as soon as stateful is enabled. Give this a try ( and remember, all changes to files can be undone with a simple reboot ):

With stateful enabled -

Copy /etc/dnsmasq.conf to /tmp

Using vi or nano, edit /tmp/dnsmasq.conf and remove the no-resolv line. Replace the servers-file line with:

resolv-file=/tmp/test.conf

Save

then run:

echo "nameserver 8.8.8.8" > /tmp/test.conf & echo "nameserver 2001:4860:4860::8888" >> /tmp/test.conf

then run:

killall dnsmasq & dnsmasq --conf-file=/tmp/dnsmasq.conf

Check logs.

 

[GHammer]

Are things working now? Anything different in the syslog?

No difference, same errors logged.

 

[GHammer]

Ah, yes, I forgot it starts doing a death loop as soon as stateful is enabled. Give this a try ( and remember, all changes to files can be undone with a simple reboot ):

With stateful enabled -

Copy /etc/dnsmasq.conf to /tmp

Using vi or nano, edit /tmp/dnsmasq.conf and remove the no-resolv line. Replace the servers-file line with: resolv-file=/tmp/test.conf

Save

then run:

echo "nameserver 8.8.8.8" > /tmp/test.conf & echo "nameserver 2001:4860:4860::8888" >> /tmp/test.conf

then run:

killall dnsmasq & dnsmasq --conf-file=/tmp/dnsmasq.conf

/tmp# killall dnsmasq | dnsmasq -

dnsmasq: junk found in command line

 

[Sean B.]

/tmp# killall dnsmasq | dnsmasq -

dnsmasq: junk found in command line

Sorry, I was restructuring the post to use code boxes to eliminate line spacing issues etc if you copy paste. I changed it a bit as well, please re-read the post.

 

[GHammer]

Sorry, I was restructuring the post to use code boxes to eliminate line spacing issues etc if you copy paste. I changed it a bit as well, please re-read the post.

Aug 19 21:08:05 dnsmasq[8556]: bad option at line 1 of /tmp/test.conf
Aug 19 21:08:05 dnsmasq[8556]: bad option at line 2 of /tmp/test.conf
Aug 19 21:08:05 dnsmasq[8556]: ignoring nameserver 127.0.0.1 - local interface

 

[Sean B.]

Aug 19 21:08:05 dnsmasq[8556]: bad option at line 1 of /tmp/test.conf
Aug 19 21:08:05 dnsmasq[8556]: bad option at line 2 of /tmp/test.conf
Aug 19 21:08:05 dnsmasq[8556]: ignoring nameserver 127.0.0.1 - local interface

Something was not done correctly when editing /tmp/dnsmasq.conf . Bad option at line 1 & 2 of /tmp/test.conf implies the resolv-file= line was not entered correctly, as dnsmasq would not be looking for options in the resolv file ( at least I don't think it would be calling them options ). Ignoring nameserver 127.0.0.1 further confirms this, as this is due to dnsmasq using /etc/resolv.conf which contains the localhost address. Basically, something about how you entered:

resolv-file=/tmp/test.conf

Did not end up correct. Or, if it does call the servers " options ", then something got messed up when you created the /tmp/test.conf file.. it should look like this:

nameserver 8.8.8.8
nameserver 2001:4860:4860::8888

If you'd like, post the conf files you made, or copy paste into a code box ( make sure to use a code box, else all the spacing will be messed up ) and I'll take a look + fix it if there's issues.

 

[GHammer]

Something was not done correctly when editing /tmp/dnsmasq.conf . Bad option at line 2 of /tmp/test.conf implies the resolve-file= line was not entered correctly, as dnsmasq would not be looking for options in the resolv file ( at least I don't think it would be calling them options ). Ignoring nameserver 127.0.0.1 further confirms this, as this is due to dnsmasq using /etc/resolv.conf which contains the localhost address. Basically, something about how you entered:

resolv-file=/tmp/test.conf

Did not end up correct. Or, if it does call the servers " options ", then something got messed up with you created the /tmp/test.conf file.. it should look like this:

nameserver 8.8.8.8
nameserver 2001:4860:4860::8888

If you'd like, post the conf files you made, or copy paste into a code box ( make sure to use a code box, else all the spacing will be messed up ) and I'll take a look + fix it if there's issues.

Aug 19 21:23:08 rc_service: watchdog 766:notify_rc start_dnsmasq
Aug 19 21:23:08 dnsmasq[9226]: warning: no upstream servers configured
Aug 19 21:23:10 kernel: Unhandled fault: alignment fault (0x92000021) at 0x000000000010c8c6

 

[GHammer]

I am unable to post the files as I am blocked by cloudflare when I try.

 

[Sean B.]

Aug 19 21:23:08 rc_service: watchdog 766:notify_rc start_dnsmasq
Aug 19 21:23:08 dnsmasq[9226]: warning: no upstream servers configured
Aug 19 21:23:10 kernel: Unhandled fault: alignment fault (0x92000021) at 0x000000000010c8c6

Was this log entry created after a successful dnsmasq start using command line with the /tmp/dnsmasq.conf file?

 

[GHammer]

Was this log entry created after a successful dnsmasq start using command line with the /tmp/dnsmasq.conf file?

Yes

 

[Sean B.]

Yes

Ok, then we're barking up the wrong tree. The issue dnsmasq is having is a symptom not a cause. You stated you're on Comcast.. when stateful is enabled, run:

ifconfig vlan2 & ifconfig br0

Providing vlan2 is the default WAN interface in Merlin firmware. Does vlan2 have an IPv6 address starting with: 2001

While br0 has an IPv6 address starting with: 2601 ?

 

[GHammer]

Ok, then we're barking up the wrong tree. The issue dnsmasq is having is a symptom not a cause. You stated you're on Comcast.. when stateful is enabled, run:

ifconfig vlan2 & ifconfig br0

Providing vlan2 is the default WAN interface in Merlin firmware. Does vlan2 have an IPv6 address starting with: 2001

While br0 has an IPv6 address starting with: 2601 ?

There are no VLANs in the router.

 

[john9527]

dnsmasq may be restarting as part of the normal startup, then the changes would be lost. To really confirm, the dnsmasq.conf edits should really be done in a dnsmasq.postconf script.
Make a /jffs/scripts/dnsmasq.postconf and set it executeable with the following

#!/bin/sh
CONFIG=$1
source /usr/sbin/helper.sh

pc_delete "no-resolv" $CONFIG
pc_replace "servers-file=/tmp/resolv.dnsmasq" "resolv-file=/tmp/test.conf" $CONFIG

 

[GHammer]

dnsmasq may be restarting as part of the normal startup, then the changes would be lost. To really confirm, the dnsmasq.conf edits should really be done in a dnsmasq.postconf script.
Make a /jffs/scripts/dnsmasq.postconf and set it executeable with the following

#!/bin/sh
CONFIG=$1
source /usr/sbin/helper.sh

pc_delete "no-resolv" $CONFIG
pc_replace "servers-file=/tmp/resolv.dnsmasq" "resolv-file=/tmp/test.conf" $CONFIG

read-only file system.

Enable JFFS custom scripts and configs is selected and router has been restarted.

 

[Sean B.]

dnsmasq may be restarting as part of the normal startup, then the changes would be lost. To really confirm, the dnsmasq.conf edits should really be done in a dnsmasq.postconf script.
Make a /jffs/scripts/dnsmasq.postconf and set it executeable with the following

#!/bin/sh
CONFIG=$1
source /usr/sbin/helper.sh

pc_delete "no-resolv" $CONFIG
pc_replace "servers-file=/tmp/resolv.dnsmasq" "resolv-file=/tmp/test.conf" $CONFIG

Good suggestion. However, I'm very much leaning toward dnsmasqs issue being a symptom not a cause. Especially with the alignment fault directly following. A dnsmasq configuration issue ( such as the implied lack of upstream servers ) should result in, at minimum: a log entry warning followed by continued operation of dnsmasq, and at worst: dnsmasq terminates only to be restarted by rc where it pomptly terminates again.. rinse & repeat. The kernel fault is coming from somewhere else, and being an alignment error, dnsmasq may be losing it's allocated memory ( where it's information is held ) due to said error and logs the issue just before the kernel logs the fault.

 

[GHammer]

Good suggestion. However, I'm very much leaning toward dnsmasqs issue being a symptom not a cause. Especially with the alignment fault directly following. A dnsmasq configuration issue ( such as the implied lack of upstream servers ) should result in, at minimum: a log entry warning followed by continued operation of dnsmasq, and at worst: dnsmasq termintes only to be restarted by rc where it pomptly terminates again.. rinse & repeat.

It is restarted by rc once every 30 seconds or so. Forever.

 

[Sean B.]

It is restarted by rc once every 30 seconds or so. Forever.

Correct, but the kernel fault would not be a part of the cycles I explained.