Comment 2 for bug 31273

Me too. In Dapper, Ethereal says *all* outgoing TCP/UDP packets have a wrong checksum, except for TCP ACK or SYN packets. I sampled DNS(UDP), HTTP and SMB(TCP).
In Breezy, there was no such problem.
Dapper's Ethereal says that the data captured in Breezy is fine.
This happens independently of promiscuous mode.

lspci reports:
0000:01:0c.0 Ethernet controller: Realtek Semiconductor Co., Ltd. RTL-8139/8139C/8139C+ (rev 10)
0000:01:0d.0 Network controller: Intel Corporation PRO/Wireless 2200BG (rev 05)

/var/log contains:
8139too Fast Ethernet driver 0.9.27
ACPI: PCI Interrupt 0000:01:0c.0[A] -> Link [LNKE] -> GSI 11 (level, low) -> IRQ 11
eth0: RealTek RTL8139 at 0xf8dfc000, 00:0b:5d:xx:xx:xx, IRQ 11
8139cp: 10/100 PCI Ethernet
8139cp: pci dev 0000:01:0c.0 (id 10ec:8139 rev 10) is not an 8139C+ compatible chip
8139cp: Try the "8139too" driver instead.
8139too Fast Ethernet driver 0.9.27
**** SET: Misaligned resource pointer: f7f176c2 Type 07 Len 0
eth0: RealTek RTL8139 at 0xf8c24000, 00:0b:5d:xx:xx:xx, IRQ 11