[Dnsmasq-discuss] dnsmasq and lxc-net integration on fedora 33
Orabuntu-LXC
gilbert at orabuntu-lxc.com
Wed Dec 23 15:00:33 GMT 2020
Next I tried listening on the veth that LXC creates when the container is
started. Once it was up, I logged into the LXC container nsa2 and ran the
command "dhclient" at the command line of the container. Now I see some
traffic on ports 67 and 68 as follows but still not understanding what is
happening here.
vethLVRkjQ: flags=4163<UP,BROADCAST,RUNNING,MULTICAST> mtu 1500
inet6 fe80::fcb2:39ff:fe74:cb61 prefixlen 64 scopeid 0x20<link>
ether fe:b2:39:74:cb:61 txqueuelen 1000 (Ethernet)
RX packets 7 bytes 586 (586.0 B)
RX errors 0 dropped 0 overruns 0 frame 0
TX packets 14 bytes 1224 (1.1 KiB)
TX errors 0 dropped 0 overruns 0 carrier 0 collisions 0
[ubuntu at f33sv1 ~]$ sudo tcpdump -i vethLVRkjQ -vvv -s 1500 '((port 67 or
port 68))'
dropped privs to tcpdump
tcpdump: listening on vethLVRkjQ, link-type EN10MB (Ethernet), capture size
1500 bytes
08:57:05.392702 IP (tos 0x10, ttl 128, id 0, offset 0, flags [none], proto
UDP (17), length 328)
0.0.0.0.bootpc > 255.255.255.255.bootps: [udp sum ok] BOOTP/DHCP,
Request from 00:16:3e:13:70:7c (oui Unknown), length 300, xid 0xb7304d0f,
Flags [none] (0x0000)
Client-Ethernet-Address 00:16:3e:13:70:7c (oui Unknown)
Vendor-rfc1048 Extensions
Magic Cookie 0x63825363
DHCP-Message Option 53, length 1: Discover
Hostname Option 12, length 4: "nsa2"
Parameter-Request Option 55, length 13:
Subnet-Mask, BR, Time-Zone, Default-Gateway
Domain-Name, Domain-Name-Server, Option 119, Hostname
Netbios-Name-Server, Netbios-Scope, MTU, Classless-Static-Route
NTP
END Option 255, length 0
PAD Option 0, length 0, occurs 35
08:57:08.398285 IP (tos 0xc0, ttl 64, id 7927, offset 0, flags [none],
proto UDP (17), length 328)
f33sv1.bootps > 10.0.3.166.bootpc: [bad udp cksum 0x1bec -> 0x19ab!]
BOOTP/DHCP, Reply, length 300, xid 0xb7304d0f, Flags [none] (0x0000)
Your-IP 10.0.3.166
Server-IP f33sv1
Client-Ethernet-Address 00:16:3e:13:70:7c (oui Unknown)
Vendor-rfc1048 Extensions
Magic Cookie 0x63825363
DHCP-Message Option 53, length 1: Offer
Server-ID Option 54, length 4: f33sv1
Lease-Time Option 51, length 4: 3600
RN Option 58, length 4: 1800
RB Option 59, length 4: 3150
Subnet-Mask Option 1, length 4: 255.255.255.0
BR Option 28, length 4: 10.0.3.255
Default-Gateway Option 3, length 4: f33sv1
Domain-Name-Server Option 6, length 4: f33sv1
Domain-Name Option 15, length 3: "lxc"
END Option 255, length 0
PAD Option 0, length 0, occurs 3
08:57:08.398693 IP (tos 0x10, ttl 128, id 0, offset 0, flags [none], proto
UDP (17), length 328)
0.0.0.0.bootpc > 255.255.255.255.bootps: [udp sum ok] BOOTP/DHCP,
Request from 00:16:3e:13:70:7c (oui Unknown), length 300, xid 0xb7304d0f,
Flags [none] (0x0000)
Client-Ethernet-Address 00:16:3e:13:70:7c (oui Unknown)
Vendor-rfc1048 Extensions
Magic Cookie 0x63825363
DHCP-Message Option 53, length 1: Request
Server-ID Option 54, length 4: f33sv1
Requested-IP Option 50, length 4: 10.0.3.166
Hostname Option 12, length 4: "nsa2"
Parameter-Request Option 55, length 13:
Subnet-Mask, BR, Time-Zone, Default-Gateway
Domain-Name, Domain-Name-Server, Option 119, Hostname
Netbios-Name-Server, Netbios-Scope, MTU, Classless-Static-Route
NTP
END Option 255, length 0
PAD Option 0, length 0, occurs 23
08:57:08.413078 IP (tos 0xc0, ttl 64, id 7931, offset 0, flags [none],
proto UDP (17), length 331)
f33sv1.bootps > 10.0.3.166.bootpc: [bad udp cksum 0x1bef -> 0x3afb!]
BOOTP/DHCP, Reply, length 303, xid 0xb7304d0f, Flags [none] (0x0000)
Your-IP 10.0.3.166
Server-IP f33sv1
Client-Ethernet-Address 00:16:3e:13:70:7c (oui Unknown)
Vendor-rfc1048 Extensions
Magic Cookie 0x63825363
DHCP-Message Option 53, length 1: ACK
Server-ID Option 54, length 4: f33sv1
Lease-Time Option 51, length 4: 3600
RN Option 58, length 4: 1800
RB Option 59, length 4: 3150
Subnet-Mask Option 1, length 4: 255.255.255.0
BR Option 28, length 4: 10.0.3.255
Default-Gateway Option 3, length 4: f33sv1
Domain-Name-Server Option 6, length 4: f33sv1
Domain-Name Option 15, length 3: "lxc"
Hostname Option 12, length 4: "nsa2"
END Option 255, length 0
On Wed, Dec 23, 2020 at 8:40 AM Orabuntu-LXC <gilbert at orabuntu-lxc.com>
wrote:
> I ran tcpdump this morning wide open (when I ran it for port 67 and port
> 68 there was zero traffic detected when starting the lxc container nsa2).
> When I ran tcpdump wide open I got the following traffic detected when the
> lxc container starts. I again tried turning off firewalld completely and
> this is still what I get as shown below. Wondering what is going on here?
>
> [ubuntu at f33sv1 ~]$ sudo tcpdump -i lxcbr0 -vvv
> dropped privs to tcpdump
> tcpdump: listening on lxcbr0, link-type EN10MB (Ethernet), capture size
> 262144 bytes
> 08:34:39.305449 IP (tos 0xc0, ttl 1, id 0, offset 0, flags [DF], proto
> IGMP (2), length 40, options (RA))
> f33sv1 > igmp.mcast.net: igmp v3 report, 1 group record(s) [gaddr
> 224.0.0.252 to_ex { }]
> 08:34:39.305469 IP6 (hlim 1, next-header Options (0) payload length: 76)
> f33sv1 > ff02::16: HBH (rtalert: 0x0000) (padn) [icmp6 sum ok] ICMP6,
> multicast listener report v2, 3 group record(s) [gaddr ff02::1:3 to_ex { }]
> [gaddr ff02::1:ff00:0 to_ex { }] [gaddr ff02::6a to_ex { }]
> 08:34:39.305542 IP6 (hlim 1, next-header Options (0) payload length: 36)
> :: > ff02::16: HBH (rtalert: 0x0000) (padn) [icmp6 sum ok] ICMP6, multicast
> listener report v2, 1 group record(s) [gaddr ff02::1:ff13:707c to_ex { }]
> 08:34:39.397672 IP6 (hlim 1, next-header Options (0) payload length: 76)
> f33sv1 > ff02::16: HBH (rtalert: 0x0000) (padn) [icmp6 sum ok] ICMP6,
> multicast listener report v2, 3 group record(s) [gaddr ff02::1:3 to_ex { }]
> [gaddr ff02::1:ff00:0 to_ex { }] [gaddr ff02::6a to_ex { }]
> 08:34:39.445676 IP6 (hlim 1, next-header Options (0) payload length: 36)
> :: > ff02::16: HBH (rtalert: 0x0000) (padn) [icmp6 sum ok] ICMP6, multicast
> listener report v2, 1 group record(s) [gaddr ff02::1:ff13:707c to_ex { }]
> 08:34:39.765786 IP6 (hlim 255, next-header ICMPv6 (58) payload length: 32)
> :: > ff02::1:ff13:707c: [icmp6 sum ok] ICMP6, neighbor solicitation, length
> 32, who has fe80::216:3eff:fe13:707c
> unknown option (14), length 8 (1):
> 0x0000: f203 5136 6f9a
> 08:34:39.891089 IP6 (hlim 255, next-header ICMPv6 (58) payload length: 32)
> f33sv1 > ff02::1:ff13:707c: [icmp6 sum ok] ICMP6, neighbor solicitation,
> length 32, who has fe80::216:3eff:fe13:707c
> source link-address option (1), length 8 (1): 00:16:3e:00:00:00
> 0x0000: 0016 3e00 0000
> 08:34:40.029649 IP (tos 0xc0, ttl 1, id 0, offset 0, flags [DF], proto
> IGMP (2), length 40, options (RA))
> f33sv1 > igmp.mcast.net: igmp v3 report, 1 group record(s) [gaddr
> 224.0.0.252 to_ex { }]
> 08:34:40.797778 IP6 (hlim 1, next-header Options (0) payload length: 36)
> fe80::216:3eff:fe13:707c > ff02::16: HBH (rtalert: 0x0000) (padn) [icmp6
> sum ok] ICMP6, multicast listener report v2, 1 group record(s) [gaddr
> ff02::1:ff13:707c to_ex { }]
> 08:34:40.797796 IP6 (hlim 255, next-header ICMPv6 (58) payload length: 16)
> fe80::216:3eff:fe13:707c > ff02::2: [icmp6 sum ok] ICMP6, router
> solicitation, length 16
> source link-address option (1), length 8 (1): 00:16:3e:13:70:7c
> 0x0000: 0016 3e13 707c
> 08:34:40.925732 IP6 (hlim 255, next-header ICMPv6 (58) payload length: 32)
> f33sv1 > ff02::1:ff13:707c: [icmp6 sum ok] ICMP6, neighbor solicitation,
> length 32, who has fe80::216:3eff:fe13:707c
> source link-address option (1), length 8 (1): 00:16:3e:00:00:00
> 0x0000: 0016 3e00 0000
> 08:34:40.925787 IP6 (hlim 255, next-header ICMPv6 (58) payload length: 32)
> fe80::216:3eff:fe13:707c > f33sv1: [icmp6 sum ok] ICMP6, neighbor
> advertisement, length 32, tgt is fe80::216:3eff:fe13:707c, Flags
> [solicited, override]
> destination link-address option (2), length 8 (1): 00:16:3e:13:70:7c
> 0x0000: 0016 3e13 707c
> 08:34:40.925797 IP6 (flowlabel 0xb6a64, hlim 1, next-header TCP (6)
> payload length: 44) f33sv1.60688 > fe80::216:3eff:fe13:707c.hostmon: Flags
> [S], cksum 0xebef (incorrect -> 0xb854), seq 2709608773, win 64800, options
> [mss 1440,sackOK,TS val 789202957 ecr 0,nop,wscale 7,tfo
> cookiereq,nop,nop], length 0
> 08:34:40.925818 IP6 (flowlabel 0xed86d, hlim 64, next-header TCP (6)
> payload length: 20) fe80::216:3eff:fe13:707c.hostmon > f33sv1.60688: Flags
> [R.], cksum 0xebd7 (incorrect -> 0xc74f), seq 0, ack 2709608774, win 0,
> length 0
> 08:34:41.693783 IP6 (hlim 1, next-header Options (0) payload length: 36)
> fe80::216:3eff:fe13:707c > ff02::16: HBH (rtalert: 0x0000) (padn) [icmp6
> sum ok] ICMP6, multicast listener report v2, 1 group record(s) [gaddr
> ff02::1:ff13:707c to_ex { }]
> 08:34:44.509930 IP6 (hlim 255, next-header ICMPv6 (58) payload length: 16)
> fe80::216:3eff:fe13:707c > ff02::2: [icmp6 sum ok] ICMP6, router
> solicitation, length 16
> source link-address option (1), length 8 (1): 00:16:3e:13:70:7c
> 0x0000: 0016 3e13 707c
> 08:34:46.045831 IP6 (hlim 255, next-header ICMPv6 (58) payload length: 32)
> fe80::216:3eff:fe13:707c > f33sv1: [icmp6 sum ok] ICMP6, neighbor
> solicitation, length 32, who has f33sv1
> source link-address option (1), length 8 (1): 00:16:3e:13:70:7c
> 0x0000: 0016 3e13 707c
> 08:34:46.045891 IP6 (hlim 255, next-header ICMPv6 (58) payload length: 24)
> f33sv1 > fe80::216:3eff:fe13:707c: [icmp6 sum ok] ICMP6, neighbor
> advertisement, length 24, tgt is f33sv1, Flags [solicited]
>
> On Wed, Dec 23, 2020 at 12:14 AM Orabuntu-LXC <gilbert at orabuntu-lxc.com>
> wrote:
>
>> Hi, I cannot get dnsmasq to issue a dhcp address via lxc-net on fedora
>> 33. I have compared it to a working system on Ubuntu 20.04 and what I find
>> is that when an lxc container starts, there is DHCPOFFER normal activity in
>> lxc-net status on Ubuntu 20.04, but not on Fedora 33 where the
>> configuration is afaik exactly the same.
>>
>> I have tried various firewalld settings in case firewalld was blocking
>> somehow, but nothing has worked including disabling firewalld entirely as
>> well as disabling selinux entirely. Tomorrow I will try tcpdump and see
>> if there are clues there. Thanks!
>>
>> --
>> Gilbert Standen
>> Creator Orabuntu-LXC
>> 914-261-4594
>> gilbert at orabuntu-lxc.com
>>
>>
>
> --
> Gilbert Standen
> Creator Orabuntu-LXC
> 914-261-4594
> gilbert at orabuntu-lxc.com
>
>
--
Gilbert Standen
Creator Orabuntu-LXC
914-261-4594
gilbert at orabuntu-lxc.com
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.thekelleys.org.uk/pipermail/dnsmasq-discuss/attachments/20201223/0ba17bcc/attachment-0001.html>
More information about the Dnsmasq-discuss
mailing list