FreeBSD dhcp failing with UDP checksum errors
I recently reinstalled Fedora (host) and I'm trying to import a
previously working FreeBSD 13 guest. It boots fine, but fails to get
an address from DHCP. In the FreeBSD boot output it prints:
Starting dhclient.
DHCPDISCOVER on vtnet0 to 255.255.255.255 port 67 interval 7
DHCPDISCOVER on vtnet0 to 255.255.255.255 port 67 interval 9
DHCPDISCOVER on vtnet0 to 255.255.255.255 port 67 interval 9
DHCPDISCOVER on vtnet0 to 255.255.255.255 port 67 interval 10
DHCPDISCOVER on vtnet0 to 255.255.255.255 port 67 interval 17
5 bad udp checksums in 5 packets
Indeed, tcpdumping the network on the host side shows that checksums
are wrong (note "bad udp cksum" in the reply message):
0.0.0.0.bootpc > 255.255.255.255.bootps: [udp sum ok] BOOTP/DHCP, Request from
52:54:00:d4:07:ab (oui Unknown), length 300, xid 0xf9ee0d34, secs 53, Flags [none]
(0x0000)
Client-Ethernet-Address 52:54:00:d4:07:ab (oui Unknown)
Vendor-rfc1048 Extensions
Magic Cookie 0x63825363
DHCP-Message (53), length 1: Discover
Requested-IP (50), length 4: freebsd.home.annexia.org
Client-ID (61), length 7: ether 52:54:00:d4:07:ab
Hostname (12), length 7: "freebsd"
Parameter-Request (55), length 10:
Subnet-Mask (1), BR (28), Time-Zone (2), Classless-Static-Route (121)
Default-Gateway (3), Domain-Name (15), Domain-Name-Server (6), Hostname (12)
Unknown (119), MTU (26)
END (255), length 0
PAD (0), length 0, occurs 20
13:07:37.304083 IP (tos 0xc0, ttl 64, id 20207, offset 0, flags [none], proto UDP (17),
length 328)
cash.bootps > 192.168.122.203.bootpc: [bad udp cksum 0x7763 -> 0x88a0!]
BOOTP/DHCP, Reply, length 300, xid 0xf9ee0d34, secs 53, Flags [none] (0x0000)
Your-IP 192.168.122.203
Server-IP cash
Client-Ethernet-Address 52:54:00:d4:07:ab (oui Unknown)
Vendor-rfc1048 Extensions
Magic Cookie 0x63825363
DHCP-Message (53), length 1: Offer
Server-ID (54), length 4: cash
Lease-Time (51), length 4: 3600
RN (58), length 4: 1800
RB (59), length 4: 3150
Subnet-Mask (1), length 4: 255.255.255.0
BR (28), length 4: 192.168.122.255
Default-Gateway (3), length 4: cash
Domain-Name-Server (6), length 4: cash
END (255), length 0
PAD (0), length 0, occurs 8
I guess this is something to do with checksum offloading. I can only
find ancient bugs related to this. How to fix? The host is:
libvirt-daemon-10.6.0-1.fc41.x86_64
dnsmasq-2.90-3.fc41.x86_64
Linux cash 6.11.0-0.rc5.20240830git20371ba12063.47.fc42.x86_64 #1 SMP PREEMPT_DYNAMIC
Fri Aug 30 15:36:28 UTC 2024 x86_64 GNU/Linux
Rich.
--
Richard Jones, Virtualization Group, Red Hat http://people.redhat.com/~rjones
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