ipv6 connectivity issues: looks like dnsmasq is crashing

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cypherstream
DD-WRT Novice


Joined: 24 Feb 2010
Posts: 30

PostPosted: Wed Jul 12, 2017 3:19    Post subject: ipv6 connectivity issues: looks like dnsmasq is crashing Reply with quote
Ever since I setup an ipv6 tunnel with Hurricane Electric today, I've noticed intermittent periods of internet connectivity issues across all devices on my network. To try to track this down I was SSH'd to the router (a Linksys 320n converted to e2000) and I was checking the processes with ps. When I have downtime I notice dnsmasq is not in the process list. This condition eventually restarts itself and when the Internet appears to be working, dnsmasq is in the process list again.

Also if I ping by name at the ddwrt root prompt I don't get anything. It just kicks me back to a command prompt.

Do you think this dnsmasq config below is causing the issue? here is my /tmp/dnsmasq.conf file

interface=br0
resolv-file=/tmp/resolv.dnsmasq
all-servers
strict-order
dhcp-leasefile=/tmp/dnsmasq.leases
dhcp-lease-max=50
dhcp-option=br0,3,192.168.1.1
dhcp-authoritative
dhcp-range=br0,192.168.1.100,192.168.1.149,255.255.255.0,1440m
stop-dns-rebind
interface=br0
domain=ddwrt,192.168.1.0/24,local
enable-ra
ra-param=br0,10,300
dhcp-range=::150,::1EFF,constructor:br0,ra-names,5m
dhcp-option=option6:dns-server,[::]
dhcp-option=option6:ntp-server,[2001:470:0:50::2]
dhcp-option=option6:domain-search,ddwrt



Also do you think there are any logs somewhere I could investigate? I do tail /var/log/messages and absolutely nothing comes across.

I'm on DD-WRT v3.0-r30880 mega (11/14/16).
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James2k
DD-WRT Guru


Joined: 23 Oct 2011
Posts: 549

PostPosted: Wed Jul 12, 2017 12:58    Post subject: Reply with quote
Syslog default log is at: /tmp/var/log/messages.
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James

Main router:

Netgear R7000 overclocked to 1.2GHz - DD-WRT v3.0-r35965M kongac

IPv6 6in4 (HE.net), OpenVPN (with PBR and split tunnelling), Entware, dnsmasq with ipset

Easy ipset support for the R7000

VPN speed: Download: 77.96 Mbps Upload: 5.00 Mbps (AES-128-CBC HMAC-SHA1)

Yes you can get 50 Mbps+ with OpenVPN on a R7000 if you configure it properly!

Previous routers:

ASUS RT-N66U - The Dark Knight
WNR2000v3 - Bought on the cheap for someone else, neutered crap
WNR3500Lv1 - First venture into the DD-WRT world
cypherstream
DD-WRT Novice


Joined: 24 Feb 2010
Posts: 30

PostPosted: Wed Jul 12, 2017 13:26    Post subject: Reply with quote
Thanks James,

I did cat on this file but its empty.

I checked and syslogd is disabled, so perhaps that's why.

Though with limited memory available I was trying to keep it down to a minimum.

# df
Filesystem 1K-blocks Used Available Use% Mounted on
rootfs 6144 6144 0 100% /
/dev/root 6144 6144 0 100% /
/dev/mtdblock/4 384 196 188 51% /jffs


So I did make a modification to dnsmasq.conf and it seems better now. I have to continue to test.

New config is as follows
interface=br0
domain=ddwrt,192.168.1.0/24,local
enable-ra
ra-param=br0,10,300
dhcp-range=::150,::1EFF,constructor:br0,ra-stateless,ra-names,12h
dhcp-option=option6:dns-server,[::]
dhcp-option=option6:ntp-server,[2001:470:0:50::2]
dhcp-option=option6:domain-search,ddwrt


Now that is set to 12 hour instead of 5 minutes, I'm wondering if that's where the crashes were occurring. I also added ra-stateless as I've seen it in other configs. I'm not sure if thats making a difference or what.

Maybe I'll enable syslogd for a few hours and then disable it, just to see if I log any crashes. I'm just not sure I the space for it.
cypherstream
DD-WRT Novice


Joined: 24 Feb 2010
Posts: 30

PostPosted: Wed Jul 12, 2017 13:36    Post subject: Reply with quote
Ok I have logging configured to papertrailapp so I can view them anywhere and not worry about taking up space on the router itself.

I'll keep my eye on it, and hopefully IF dnsmasq crashes, there is a log regarding it. Maybe it will crash every 12h now instead of every 5m.
cypherstream
DD-WRT Novice


Joined: 24 Feb 2010
Posts: 30

PostPosted: Thu Jul 13, 2017 1:59    Post subject: Reply with quote
Well since I made that change to dnsmasq.conf above, I have not logged a single crash, and web browsing did not stall.

I highly recommend looking at papertrailapp.com. Now that I'm sending syslogs there I can alert on anything unusual or just send periodic summaries. I was not aware of all of the IP's from APNIC and RIPE trying to SSH to the router. I would forward a non-standard port, but at work non-standard ports are blocked outbound and then I wouldn't be able to tunnel back home to send WOL and RDP over SSH, or browse the Internet using my connection.
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