On Mon, Sep 20, 2010 at 02:12:40PM +0200, xming wrote: > Hi, > > I think I am hitting this, in a weird way :D. Running 0.12.90, > vhost_net and kernel 2.6.35.4, I have troubles to get dhcp clients to > work except an old dhcp client "pump" seems to work out of the box. > Below are the output of dhcpcd, isc's dhcp client and busybox' udhcpc. > > My dhcp server is in a guest with vhost_net running dnsmasq. Clients > which do not use vhost_net (plain virtio, e1000 and physical machines) > do not have any problems. The dhcp server itself is a dhcp client and > uses dhcpcd to get lease from ADSL modem w/o issues. > When the dhcp server is not using vhost_net, then all clients can get a lease. > > So my conclusion so far is that when the server is using vhost_net and > clients are using vhost_net (and above mentioned software), then it's > getting invalid/checksum error UDP. the only working DHCP client is > pump. Newer versions of dhclient should also be OK: they detect that checksum is missing in the packet. Try it e.g. with a recent fedora guest as a client. To solve the problem for old clients, recent kernels and iptables have support for CHECKSUM target. You can use this target to compute and fill in the checksum in a packet that lacks a checksum. Typical expected use: iptables -A POSTROUTING -t mangle -p udp --dport bootpc \ -j CHECKSUM --checksum-fill libvirt will program these for you if it sets up the server, maybe there needs a flag to tell it that server is local. > # dhcpcd > dhcpcd[9089]: version 5.2.7 starting > dhcpcd[9089]: eth0: broadcasting for a lease > dhcpcd[9089]: eth0: invalid UDP packet from 192.168.1.1 > dhcpcd[9089]: eth0: invalid UDP packet from 192.168.1.1 > dhcpcd[9089]: eth0: invalid UDP packet from 192.168.1.1 > dhcpcd[9089]: eth0: invalid UDP packet from 192.168.1.1 > dhcpcd[9089]: timed out > dhcpcd[9089]: allowing 8 seconds for IPv4LL timeout > dhcpcd[9089]: eth0: probing for an IPv4LL address > dhcpcd[9089]: eth0: checking for 169.254.195.227 > dhcpcd[9089]: eth0: using IPv4LL address 169.254.195.227 > dhcpcd[9089]: forked to background, child pid 9109 > > # dhclient > Internet Systems Consortium DHCP Client V3.1.2p1-Gentoo > Copyright 2004-2009 Internet Systems Consortium. > All rights reserved. > For info, please visit http://www.isc.org/sw/dhcp/ > > Listening on LPF/eth0/00:16:3e:00:07:01 > Sending on LPF/eth0/00:16:3e:00:07:01 > Sending on Socket/fallback > DHCPDISCOVER on eth0 to 255.255.255.255 port 67 interval 7 > DHCPDISCOVER on eth0 to 255.255.255.255 port 67 interval 7 > DHCPDISCOVER on eth0 to 255.255.255.255 port 67 interval 7 > DHCPDISCOVER on eth0 to 255.255.255.255 port 67 interval 13 > DHCPDISCOVER on eth0 to 255.255.255.255 port 67 interval 13 > 5 bad udp checksums in 5 packets > DHCPDISCOVER on eth0 to 255.255.255.255 port 67 interval 14 > No DHCPOFFERS received. > No working leases in persistent database - sleeping. > > > # busybox udhcpc > ### adapter index 2 > ### adapter hardware address 00:16:3e:00:07:01 > udhcpc (v1.13.2) started > ### vfork'ing and execle'ing /usr/share/udhcpc/default.script > udhcpc: exec /usr/share/udhcpc/default.script: No such file or directory > ### entering raw listen mode > ### opening raw socket on ifindex 2 > ### got raw socket fd 5 > ### attached filter to raw socket fd 5 > ### bound to raw socket fd 5 > ### adding option 0x35 > ### adding option 0x3d > ### adding option 0x3c > ### adding option 0x39 > Sending discover... > ### Waiting on select... > udhcpc: packet with bad UDP checksum received, ignoring > ### Waiting on select... > ### adding option 0x35 > ### adding option 0x3d > ### adding option 0x3c > ### adding option 0x39 > Sending discover... > ### Waiting on select... > udhcpc: packet with bad UDP checksum received, ignoring > ### Waiting on select... > ### adding option 0x35 > ### adding option 0x3d > ### adding option 0x3c > ### adding option 0x39 > Sending discover... > ### Waiting on select... > udhcpc: packet with bad UDP checksum received, ignoring > ### Waiting on select... > ### vfork'ing and execle'ing /usr/share/udhcpc/default.script > udhcpc: exec /usr/share/udhcpc/default.script: No such file or directory > ### Waiting on select... > ### adding option 0x35 > ### adding option 0x3d > ### adding option 0x3c > ### adding option 0x39 > Sending discover... > ### Waiting on select... > udhcpc: packet with bad UDP checksum received, ignoring > ### Waiting on select... > -- > To unsubscribe from this list: send the line "unsubscribe kvm" in > the body of a message to majordomo@xxxxxxxxxxxxxxx > More majordomo info at http://vger.kernel.org/majordomo-info.html -- To unsubscribe from this list: send the line "unsubscribe kvm" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
