Re: dnsmasq dhcp failure

I just had dnsmasq stop serving requests.  Restart of dnsmasq required.   

LEAF Bering-uClibc 7.1.3-rc2 Rev 1, up for 20 days



On Friday, 9 September 2022 10:20:15 PM AEDT Erich Titl wrote:
> Hi Folks
> 
> Am 29.08.2022 um 00:31 schrieb marko via leaf-user:
> 
> > Hi ET,
> > 
> > I have run leaf for a very long time, normally on fast hardware with
> > plenty of
 memory.
> > 
> > I've never seen dnsmasq not serve requests or allocate leases.
> > 
> > I think dnsmasq fits the smaller network that is a bit complex scenario
> > very
 well.  Making it more complex would be a mistake as would making it
> > more like commodity routers which have many functions now.
> 
> 
> I can show now that with assigning a fixed address to a win10 client I 
> can connect to the uplink LEAF system and the internet correctly. So 
> obviously the dhcp request is _not_ handled correctly.
> 
> Once connected to the LEAF box I see the folloging on the internal
> interface
 
> SALT# tcpdump -i br0 port 67
> tcpdump: verbose output suppressed, use -v[v]... for full protocol decode
> listening on br0, link-type EN10MB (Ethernet), snapshot length 262144 bytes
> 11:51:55.058168 IP .bootpc > 255.255.255.255.bootps: BOOTP/DHCP, Request
> from 34:46:ec:b2:ab:e7 (oui Unknown), length 324
> 11:51:55.061890 IP .bootpc > 255.255.255.255.bootps: BOOTP/DHCP, Request 
> from 34:46:ec:b2:ab:e7 (oui Unknown), length 324
> 11:52:00.059480 IP .bootpc > 255.255.255.255.bootps: BOOTP/DHCP, Request 
> from 34:46:ec:b2:ab:e7 (oui Unknown), length 324
> 11:52:04.063118 IP .bootpc > 255.255.255.255.bootps: BOOTP/DHCP, Request 
> from 34:46:ec:b2:ab:e7 (oui Unknown), length 318
> 11:52:09.065633 IP .bootpc > 255.255.255.255.bootps: BOOTP/DHCP, Request 
> from 34:46:ec:b2:ab:e7 (oui Unknown), length 318
> 11:52:14.068486 IP .bootpc > 255.255.255.255.bootps: BOOTP/DHCP, Request 
> from 34:46:ec:b2:ab:e7 (oui Unknown), length 318
> 11:52:19.077023 IP .bootpc > 255.255.255.255.bootps: BOOTP/DHCP, Request 
> from 34:46:ec:b2:ab:e7 (oui Unknown), length 318
> 
> 
> So again, it looks like dhcp requests are coming in but are not replied to.
> 
> So for completeness I copy the configuration here
> 
> SALT# ip addr
> 1: lo: <LOOPBACK,UP,LOWER_UP> mtu 65536 qdisc noqueue state UNKNOWN 
> group default qlen 1000
>      link/loopback 00:00:00:00:00:00 brd 00:00:00:00:00:00
>      inet 127.0.0.1/8 scope host lo
>         valid_lft forever preferred_lft forever
> 2: dummy0: <BROADCAST,NOARP> mtu 1500 qdisc noop state DOWN group 
> default qlen 1000
>      link/ether 12:66:bb:45:54:68 brd ff:ff:ff:ff:ff:ff
> 3: eth0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc pfifo_fast 
> master br0 state UP group default qlen 1000
>      link/ether 00:0d:b9:04:6e:d8 brd ff:ff:ff:ff:ff:ff
> 4: wlan0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc noqueue state 
> UP group default qlen 1000
>      link/ether 04:f0:21:17:32:8e brd ff:ff:ff:ff:ff:ff
>      inet 192.168.1.69/24 brd 192.168.1.255 scope global dynamic 
> noprefixroute wlan0
>         valid_lft 2522sec preferred_lft 2072sec
> 5: wlan1: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc noqueue 
> master br0 state UP group default qlen 1000
>      link/ether 04:f0:21:17:32:8b brd ff:ff:ff:ff:ff:ff
> 6: br0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc noqueue state 
> UP group default qlen 1000
>      link/ether 00:0d:b9:04:6e:d8 brd ff:ff:ff:ff:ff:ff
>      inet 192.168.217.1/24 scope global br0
>         valid_lft forever preferred_lft forever
> 
> Restarting shorewall took forever so I looked at the processes running 
> and I found that dnsmasq is quite prominent in the CPU score.
> 
> Mem: 47060K used, 9576K free, 2448K shrd, 0K buff, 2448K cached
> CPU: 97.2% usr  1.3% sys  0.0% nic  0.0% idle  0.0% io  0.0% irq  1.3% sirq
> Load average: 2.35 2.55 1.87 2/55 8490
>    PID  PPID USER     STAT   VSZ %VSZ %CPU COMMAND
>   1724     1 nobody   R     1200  2.1 97.4 /usr/sbin/dnsmasq
>   8330  8283 root     R     1320  2.3  1.5 top
>   8281  1989 root     S     4136  7.2  0.5 sshd: root@pts/2
>   2005     1 root     S      968  1.7  0.1 /usr/sbin/cron
>   8380     2 root     IW       0  0.0  0.1 [kworker/u2:0-ph]
>   1628     1 root     S    12600 22.1  0.0 /usr/sbin/rsyslogd
> 
> These systems used to run fine in the past so I am suspicious that newer 
> linux software starts to become bloatware just like on the winblows side.
> 
> I definitely will replace dnsmasq and see if a combination of dnscache 
> and dhcpd works better.
> 
> cheers
> 
> ET
> 
> 
> 





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