Hi,
i have trying to play with KVM on gentoo and stumbled upon a guest reseting
incoming connection. (looks like qemu cheating the guest by sending
fake tcp-reset).
below i send typical ssh session:
tcpdump: WARNING: eth0: no IPv4 address assigned
tcpdump: verbose output suppressed, use -v or -vv for full protocol decode
listening on eth0, link-type EN10MB (Ethernet), capture size 68 bytes
16:53:55.533949 IP Y.Y.79.34.59793 > X.X.79.231.22: S
41315573:41315573(0) win 5840 <mss 1460,[|tcp]>
16:53:55.534211 IP X.X.79.231.22 > Y.Y.79.34.59793: S
3726054219:3726054219(0) ack 41315574 win 5792 <mss 1460,[|tcp]>
16:53:55.536362 IP Y.Y.79.34.59793 > X.X.79.231.22: . ack 1 win 92
<nop,nop,timestamp[|tcp]>
!---> 16:53:55.536514 IP X.X.79.231.22 > Y.Y.79.34.59793: R
3726054220:3726054220(0) win 0
^C4 packets captured
4 packets received by filter
0 packets dropped by kernel
tcpdump: verbose output suppressed, use -v or -vv for full protocol decode
listening on br0, link-type EN10MB (Ethernet), capture size 68 bytes
16:53:55.533949 IP Y.Y.79.34.59793 > X.X.79.231.22: S
41315573:41315573(0) win 5840 <mss 1460,[|tcp]>
16:53:55.534199 IP X.X.79.231.22 > Y.Y.79.34.59793: S
3726054219:3726054219(0) ack 41315574 win 5792 <mss 1460,[|tcp]>
!---> 16:53:55.534228 IP Y.Y.79.34.59793 > X.X.79.231.22: R
41315574:41315574(0) win 0
16:53:55.536362 IP Y.Y.79.34.59793 > X.X.79.231.22: . ack 1 win 92
<nop,nop,timestamp[|tcp]>
16:53:55.536504 IP X.X.79.231.22 > Y.Y.79.34.59793: R
3726054220:3726054220(0) win 0
16:53:55.536530 IP Y.Y.79.34.59793 > X.X.79.231.22: R
4253651723:4253651723(0) ack 1 win 0
eth0 - host's hardware interface
br0 - interface bridging eth0 and guests tap
~ # brctl show br0
bridge name bridge id STP enabled interfaces
br0 8000.003048def1bc no eth0
tap_dev_ext
afaics the only reqirement to trigger this behaviour is a *default*
route set for the guest kernel,
i.e. somthing like.
ip route add 0/0 gw X.X.79.1
inside guest leads to fake reset, but
ip route add Y.Y.79.34/32 gw X.X.79.1
works as expected.
on the other side seems like outgoing tcp sessions aren't affected.
I'm stuck. No ideia where it come from and how to debug :( any ideas?
--
Best regards.
Alexander Y. Fomichev <git.u...@gmail.com>
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