> In article <Pine.LNX.3.96.980205020351.3022C-100000@kanga.eecs.umich.edu> you wrote:
>
> : I have been unable to get the arp address of our gateway when running
>
> ifconfig
> route -n
Hi Alexey,
Below is a different machine with the same problem. I use this
machine because it's on the same network as another linux machine so I
can run tcpdump to see what's happening.
Here is the info you requested: As you see below, the machine is
141.213.10.6 and unable to get the arp address of 141.213.10.1 on the
2.1.x kernel. (tcpdump log at bottom).
dtw# ifconfig
lo Link encap:Local Loopback
inet addr:127.0.0.1 Bcast:0.0.0.0 Mask:255.0.0.0
UP LOOPBACK RUNNING MTU:3584 Metric:1
RX packets:42 error:0 dropped:0 over:0 frame:0
TX packets:42 error:0 dropped:0 over:0 carrier:0 coll:0
eth0 Link encap:Ethernet HWaddr 00:A0:C9:98:67:5F
inet addr:141.213.10.6 Bcast:141.213.10.255 Mask:255.255.255.0
UP BROADCAST RUNNING MULTICAST MTU:1500 Metric:1
RX packets:1842 error:0 dropped:0 over:0 frame:0
TX packets:1207 error:0 dropped:0 over:0 carrier:0 coll:475
Interrupt:10 Base address:0xff80
dtw# route -n
Kernel IP routing table
Destination Gateway Genmask Flags Metric Ref Use Iface
141.213.10.0 0.0.0.0 255.255.255.0 U 0 0 0 eth0
127.0.0.0 0.0.0.0 255.0.0.0 U 0 0 0 lo
0.0.0.0 141.213.10.1 0.0.0.0 UG 0 0 0 eth0
dtw# cat /proc/net/arp
IP address HW type Flags HW address Mask Device
141.213.10.1 0x1 0x0 00:00:00:00:00:00 * eth0
141.213.10.40 0x1 0x2 08:00:20:08:30:8E * eth0
141.213.10.204 0x1 0x2 08:00:20:75:D6:4A * eth0
141.213.10.237 0x1 0x2 00:A0:C9:25:3F:46 * eth0
dtw# arp
Address HWtype HWaddress Flags Mask Iface
eecs2s-gw.eecs.umich.ed (incomplete) eth0
lima.eecs.umich.edu ether 08:00:20:08:30:8E C eth0
beelzebub.eecs.umich.ed ether 08:00:20:75:D6:4A C eth0
germany.eecs.umich.edu ether 00:A0:C9:25:3F:46 C eth0
TCPDUMP output. Below I show the difference betwen 2.1.78 and 2.0.33.
-------
I am calling tcpdump as:
tcpdump -e -x -l -n -i eth0 host dtw and not germany
where dtw is the machine that has the problem, and germany is the machine I am
running tcpdump on.
on 2.1.78, here's what I see. The machine dtw comes up, looks for the
gateway at 141.213.10.1. There are no replies back to machine and it
is never able to figure out the gateway HW address. However, is is
able to communicate with other machines on the same subnet.
17:06:07.457120 0:a0:c9:98:67:5f ff:ff:ff:ff:ff:ff 0806 60: arp who-has 141.213.10.1 tell 141.213.10.6
0001 0800 0604 0001 00a0 c998 675f 8dd5
0a06 0000 0000 0000 8dd5 0a01 7e7e 7e7e
7e7e 7e7e 7e7e 7e7e 7e7e 7e7e 7e7e
17:06:11.337114 0:a0:c9:98:67:5f ff:ff:ff:ff:ff:ff 0806 60: arp who-has 141.213.10.204 tell 141.213.10.6
0001 0800 0604 0001 00a0 c998 675f 8dd5
0a06 0000 0000 0000 8dd5 0acc 7e7e 7e7e
7e7e 7e7e 7e7e 7e7e 7e7e 7e7e 7e7e
17:06:12.447112 0:a0:c9:98:67:5f ff:ff:ff:ff:ff:ff 0806 60: arp who-has 141.213.10.1 tell 141.213.10.6
0001 0800 0604 0001 00a0 c998 675f 8dd5
0a06 0000 0000 0000 8dd5 0a01 7e7e 7e7e
7e7e 7e7e 7e7e 7e7e 7e7e 7e7e 7e7e
17:10:08.926746 0:a0:c9:98:67:5f ff:ff:ff:ff:ff:ff 0806 60: arp who-has 141.213.10.216 tell 141.213.10.6
0001 0800 0604 0001 00a0 c998 675f 8dd5
0a06 0000 0000 0000 8dd5 0ad8 7e7e 7e7e
7e7e 7e7e 7e7e 7e7e 7e7e 7e7e 7e7e
17:10:08.926746 0:60:b0:18:f5:78 0:a0:c9:98:67:5f 0806 60: arp reply 141.213.10.216 is-at 0:60:b0:18:f5:78
0001 0800 0604 0002 0060 b018 f578 8dd5
0ad8 00a0 c998 675f 8dd5 0a06 7e7e 7e7e
7e7e 7e7e 7e7e 7e7e 7e7e 7e7e 7e7e
17:10:08.926746 0:a0:c9:98:67:5f 0:60:b0:18:f5:78 0800 98: 141.213.10.6 > 141.213.10.216: icmp: echo request
4500 0054 0199 0000 4001 4888 8dd5 0a06
8dd5 0ad8 0800 256e a600 0000 b02a da34
a92e 0e00 0809 0a0b 0c0d 0e0f 1011 1213
1415 1617 1819
17:10:08.926746 0:60:b0:18:f5:78 0:a0:c9:98:67:5f 0800 98: 141.213.10.216 > 141.213.10.6: icmp: echo reply
4500 0054 935a 0000 ff01 f7c5 8dd5 0ad8
8dd5 0a06 0000 2d6e a600 0000 b02a da34
a92e 0e00 0809 0a0b 0c0d 0e0f 1011 1213
1415 1617 1819
on 2.0.33, here's what I see. The machine dtw starts by looking for
141.213.10.1. I don't see any replies back to it, but in the next
packet leaving dtw, it already has figured out the gatway somehow (ethernet
address 00:00:0C:14:6C:D9).
16:55:51.449098 0:a0:c9:98:67:5f ff:ff:ff:ff:ff:ff 0806 60: arp who-has 141.213.10.1 tell 141.213.10.6
0001 0800 0604 0001 00a0 c998 675f 8dd5
0a06 0000 0000 0000 8dd5 0a01 7e7e 7e7e
7e7e 7e7e 7e7e 7e7e 7e7e 7e7e 7e7e
16:55:51.969098 0:a0:c9:98:67:5f 0:0:c:14:6c:d9 0800 60: 141.213.10.6.1025 > 128.63.2.53.53: 29052 NS? . (17)
4500 002d 0005 0000 4011 606c 8dd5 0a06
803f 0235 0401 0035 0019 6cb9 717c 0000
0001 0000 0000 0000 0000 0200 017e
16:55:54.169098 0:a0:c9:98:67:5f 0:0:c:14:6c:d9 0800 84: 141.213.10.6.1025 > 128.63.2.53.53: 29053 (42)
4500 0046 0009 0000 4011 604f 8dd5 0a06
803f 0235 0401 0035 0032 989d 717d 0000
0001 0000 0000 0000 0874 696d 6573 7276
3105 656e 6769
16:55:55.009098 0:a0:c9:98:67:5f 0:0:c:14:6c:d9 0800 60: 141.213.10.6.1025 > 192.5.5.241.53: 29052 NS? . (17)
4500 002d 000b 0000 4011 1ce4 8dd5 0a06
c005 05f1 0401 0035 0019 2937 717c 0000
0001 0000 0000 0000 0000 0200 017e
2.0.33:dtw# arp
Address HWtype HWaddress Flags Mask Iface
eecs2s-gw.eecs.umich.ed ether 00:00:0C:14:6C:D9 C eth0
germany.eecs.umich.edu ether 00:A0:C9:25:3F:46 C eth0
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