hi all,

i am running ubuntu 10.04 on a small server with several interfaces on the same subnet.

with my current setup the client receives a working ip,
but after i see a client arp request towards the (directly) connected interface no reply is coming back
i checked cables,used tcpdump...
there is no firewall running (so default iptables).
network manager is no longer installed.

recently i tried switching the client to all my other interfaces and i noticed one of them always worked...the one defined by the 'local link'.
i have read some wiki and other sources but i can not yet determine the relation between both... unless i have made a fundamental configuration mistake somewhere and the only available route (link local with metric 1000) is being used.
after a reboot the local link seems to be attached to another interface.

i have added most of the main config files/logs down here.

all suggestions are appreciated.



server dhcpd config================
subnet 10.0.4.0 netmask 255.255.255.224 {
option routers 10.0.4.10;
range 10.0.4.17 10.0.4.30;
option broadcast-address 10.0.4.31;
}


server interfaces=============
=== only eth0=client and eth5='upstream' connected ======

auto eth1
iface eth1 inet static
address 10.0.4.11
network 10.0.4.0
netmask 255.255.255.224

auto eth2
iface eth2 inet static
address 10.0.4.12
network 10.0.4.0
netmask 255.255.255.224

auto eth3
iface eth3 inet static
address 10.0.4.13
network 10.0.4.0
netmask 255.255.255.224

auto eth4
iface eth4 inet static
address 10.0.4.14
network 10.0.4.0
netmask 255.255.255.224

auto eth5
iface eth5 inet dhcp

auto wlan0
iface wlan0 inet static
address 10.0.4.16
network 10.0.4.0
netmask 255.255.255.224

auto eth0
iface eth0 inet static
address 10.0.4.10
network 10.0.4.0
netmask 255.255.255.224

server route=====================
admin1@admin1-desktop:~$ route
Kernel IP routing table
Destination Gateway Genmask Flags Metric Ref Use Iface
10.0.4.0 * 255.255.255.224 U 0 0 0 eth2
10.0.4.0 * 255.255.255.224 U 0 0 0 eth3
10.0.4.0 * 255.255.255.224 U 0 0 0 eth4
10.0.4.0 * 255.255.255.224 U 0 0 0 eth1
10.0.4.0 * 255.255.255.224 U 0 0 0 eth0
10.0.4.0 * 255.255.255.224 U 0 0 0 wlan0
10.0.2.0 * 255.255.255.0 U 0 0 0 eth5
link-local * 255.255.0.0 U 1000 0 0 eth2
default 10.0.2.1 0.0.0.0 UG 100 0 0 eth5

server tcpdump eth0 ===============================

admin1@admin1-desktop:~$ sudo tcpdump -i eth0
tcpdump: verbose output suppressed, use -v or -vv for full protocol decode
listening on eth0, link-type EN10MB (Ethernet), capture size 96 bytes
14:34:30.287409 IP 0.0.0.0.bootpc > 255.255.255.255.bootps: BOOTP/DHCP, Request from 00:17:a4:dd:54:15 (oui Unknown), length 300
14:34:30.302085 IP admin1-desktop.local.bootps > 10.0.4.17.bootpc: BOOTP/DHCP, Reply, length 300
14:34:30.427229 IP admin1-desktop.local.mdns > 224.0.0.251.mdns: 0 PTR (QM)? 255.255.255.255.in-addr.arpa. (46)
14:34:31.428522 IP admin1-desktop.local.mdns > 224.0.0.251.mdns: 0 PTR (QM)? 255.255.255.255.in-addr.arpa. (46)
14:34:33.287640 IP 0.0.0.0.bootpc > 255.255.255.255.bootps: BOOTP/DHCP, Request from 00:17:a4:dd:54:15 (oui Unknown), length 300
14:34:33.300920 IP admin1-desktop.local.bootps > 10.0.4.17.bootpc: BOOTP/DHCP, Reply, length 300
14:34:33.322594 IP 10.0.4.17 > IGMP.MCAST.NET: igmp v3 report, 1 group record(s)
14:34:33.430923 IP admin1-desktop.local.mdns > 224.0.0.251.mdns: 0 PTR (QM)? 255.255.255.255.in-addr.arpa. (46)
14:34:33.462556 IP 10.0.4.17.mdns > 224.0.0.251.mdns: 0 [4q] [7n][|domain]
14:34:33.470962 IP 10.0.4.17.mdns > 224.0.0.251.mdns: 0*- [0q] 2/0/0[|domain]
14:34:33.712172 IP 10.0.4.17.mdns > 224.0.0.251.mdns: 0 [4q] [7n][|domain]
14:34:33.962406 IP 10.0.4.17.mdns > 224.0.0.251.mdns: 0 [4q] [7n][|domain]
14:34:34.162772 IP 10.0.4.17.mdns > 224.0.0.251.mdns: 0*- [0q] 7/0/0[|domain]
14:34:34.381406 ARP, Request who-has admin1-desktop.local tell 10.0.4.17, length 46
14:34:34.567973 IP 10.0.4.17.mdns > 224.0.0.251.mdns: 0*- [0q] 2/0/0[|domain]
14:34:35.259491 IP 10.0.4.17.mdns > 224.0.0.251.mdns: 0*- [0q] 7/0/0[|domain]
14:34:35.381248 ARP, Request who-has admin1-desktop.local tell 10.0.4.17, length 46
14:34:35.555493 IP admin1-desktop.local.mdns > 224.0.0.251.mdns: 0 PTR (QM)? 0.0.0.0.in-addr.arpa. (38)
14:34:36.381108 ARP, Request who-has admin1-desktop.local tell 10.0.4.17, length 46
14:34:36.556948 IP admin1-desktop.local.mdns > 224.0.0.251.mdns: 0 PTR (QM)? 0.0.0.0.in-addr.arpa. (38)
14:34:36.664800 IP 10.0.4.17.mdns > 224.0.0.251.mdns: 0*- [0q] 6/0/0[|domain]
14:34:37.356191 IP 10.0.4.17.mdns > 224.0.0.251.mdns: 0*- [0q] 7/0/0[|domain]
14:34:38.558403 IP admin1-desktop.local.mdns > 224.0.0.251.mdns: 0 PTR (QM)? 0.0.0.0.in-addr.arpa. (38)
14:34:39.380651 ARP, Request who-has admin1-desktop.local tell 10.0.4.17, length 46
14:34:39.472656 IP 10.0.4.17 > IGMP.MCAST.NET: igmp v3 report, 1 group record(s)
14:34:40.380503 ARP, Request who-has admin1-desktop.local tell 10.0.4.17, length 46
14:34:40.677254 IP admin1-desktop.local.mdns > 224.0.0.251.mdns: 0 PTR (QM)? 17.4.0.10.in-addr.arpa. (40)
14:34:40.677538 IP 10.0.4.17.mdns > 224.0.0.251.mdns: 0*- [0q] 1/0/0 (Cache flush) PTR[|domain]
14:34:41.380359 ARP, Request who-has admin1-desktop.local tell 10.0.4.17, length 46
14:34:41.678645 IP admin1-desktop.local.mdns > 224.0.0.251.mdns: 0 PTR (QM)? 17.4.0.10.in-addr.arpa. (40)
14:34:41.678909 IP 10.0.4.17.mdns > 224.0.0.251.mdns: 0*- [0q] 1/0/0 (Cache flush) PTR[|domain]
14:34:43.680280 IP admin1-desktop.local.mdns > 224.0.0.251.mdns: 0 PTR (QM)? 17.4.0.10.in-addr.arpa. (40)
14:34:43.680571 IP 10.0.4.17.mdns > 224.0.0.251.mdns: 0*- [0q] 1/0/0 (Cache flush) PTR[|domain]
14:34:44.399907 ARP, Request who-has admin1-desktop.local tell 10.0.4.17, length 46
14:34:45.399756 ARP, Request who-has admin1-desktop.local tell 10.0.4.17, length 46
14:34:45.795069 IP admin1-desktop.local.mdns > 224.0.0.251.mdns: 0 PTR (QM)? 10.4.0.10.in-addr.arpa. (40)
14:34:45.795568 IP admin1-desktop.local.mdns > 224.0.0.251.mdns: 0*- [0q] 1/0/0 (Cache flush) PTR[|domain]
14:34:46.015640 IP admin1-desktop.local.mdns > 224.0.0.251.mdns: 0 PTR (QM)? 251.0.0.224.in-addr.arpa. (42)
14:34:46.399597 ARP, Request who-has admin1-desktop.local tell 10.0.4.17, length 46
14:34:47.016205 IP admin1-desktop.local.mdns > 224.0.0.251.mdns: 0 PTR (QM)? 251.0.0.224.in-addr.arpa. (42)
14:34:49.017692 IP admin1-desktop.local.mdns > 224.0.0.251.mdns: 0 PTR (QM)? 251.0.0.224.in-addr.arpa. (42)
14:34:49.403149 ARP, Request who-has admin1-desktop.local tell 10.0.4.17, length 46
14:34:50.402997 ARP, Request who-has admin1-desktop.local tell 10.0.4.17, length 46
14:34:51.402853 ARP, Request who-has admin1-desktop.local tell 10.0.4.17, length 46
14:34:52.683690 ARP, Request who-has admin1-desktop.local tell 10.0.4.17, length 46
14:34:53.683518 ARP, Request who-has admin1-desktop.local tell 10.0.4.17, length 46
...


client : 10.0.4.17/bc 100.4.31/mask 255.255.255.224 == route ============
10.0.4.0 * 255.255.255.223 eth0
local * 255.255.0.0. eth0
default 10.0.4.10 0.0.0.0 eth0

client: arping 10.0.4.10 ================
14:22:45.194182 ARP, Request who-has admin1-desktop.local (Broadcast) tell 10.0.4.17, length 46
14:22:46.194110 ARP, Request who-has admin1-desktop.local (Broadcast) tell 10.0.4.17, length 46
14:22:47.194029 ARP, Request who-has admin1-desktop.local (Broadcast) tell 10.0.4.17, length 46
14:22:48.193935 ARP, Request who-has admin1-desktop.local (Broadcast) tell 10.0.4.17, length 46
14:22:49.193861 ARP, Request who-has admin1-desktop.local (Broadcast) tell 10.0.4.17, length 46
14:22:50.193784 ARP, Request who-has admin1-desktop.local (Broadcast) tell 10.0.4.17, length 46

i have installed a test version of 10.04.
after that the only thing i did was changing the interfaces and the dhcpd.conf file.
upon reboot i encoutered the same problem.

there must be a fundamental flaw in my setup...

Why do you have a 223 here in your route:

client : 10.0.4.17/bc 100.4.31/mask 255.255.255.224 == route ============
10.0.4.0 * 255.255.255.223 eth0

I also wonder, why you attached so many interfaces within the same network 10.0.4.0? If you want to connect just one particular machine thereto, you could create a route for only this address and it would shot up as "UH" in route.

small typing error, that 223 is a 224.
since i have several interfaces wo (currently) any need for several different routes/subnets i thought why would i not group some interfaces together to act as if it was a regular switch device.