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From: William S. <wst...@po...> - 2000-09-07 20:44:48
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Good day, James, Jeff, et al,
I've had some luck with the new Ethernet code, but some things
aren't working exactly as I'd expect. May I bore you with the details?
:-)
The UML is 192.168.0.12 with mac address cc0:ff:ee:c0:ff:ee, the
host is 192.168.0.254 with mac address FE:FD:00:00:00:00. Network 100 for
simplicity.
In host, as root:
ifconfig tap0 192.168.0.254 netmask 255.255.255.0 broadcast 192.168.0.255 up
um_eth_net_util tap0 100
Gives:
[root@sparrow /root]# um_eth_net_util tap0 100
/dev/tap0: No such file or directory
PHY: tap0
connect
From uml, .12, I try to ping the host:
bash# ping 192.168.0.254
PING 192.168.0.254 (192.168.0.254) from 192.168.0.12 : 56(84) bytes of data.
From 192.168.0.12 (192.168.0.12): Destination Host Unreachable
From 192.168.0.12 (192.168.0.12): Destination Host Unreachable
...
The output from um_eth_net_util is:
05 100 -> ff ff ff ff ff ff c0 ff ee c0 ff ee 08 06 00 01 -> 04
05 100 -> ff ff ff ff ff ff c0 ff ee c0 ff ee 08 06 00 01 -> 04
...
Running tcpdump on the host gives:
[root@sparrow /root]# tcpdump -i tap0 -qtn
User level filter, protocol ALL, datagram packet socket
tcpdump: listening on tap0
> 0:0:0:0:0:0 > c0:ff:ee:c0:ff:ee null I (s=4,r=0,R) len=24
0604 0001 c0ff eec0 ffee c0a8 000c 0000
0000 0000 c0a8 00fe
> 0:0:0:0:0:0 > c0:ff:ee:c0:ff:ee null I (s=4,r=0,R) len=24
0604 0001 c0ff eec0 ffee c0a8 000c 0000
0000 0000 c0a8 00fe
...
-----------------------------------------------------------------
In the above tests, the host has no file called /dev/tap0. Let's
make one:
mknod /dev/tap0 c 36 16
Now, try the same again:
[root@sparrow /root]# um_eth_net_util tap0 100
TAP: tap0
05 100 -> ff ff ff ff ff ff c0 ff ee c0 ff ee 08 06 00 01 -> 04
05 100 -> ff ff ff ff ff ff c0 ff ee c0 ff ee 08 06 00 01 -> 04
...
bash# ping 192.168.0.254
PING 192.168.0.254 (192.168.0.254) from 192.168.0.12 : 56(84) bytes of data.
From 192.168.0.12 (192.168.0.12): Destination Host Unreachable
From 192.168.0.12 (192.168.0.12): Destination Host Unreachable
[root@sparrow /root]# tcpdump -i tap0 -qtn
User level filter, protocol ALL, datagram packet socket
tcpdump: listening on tap0
B arp who-has 192.168.0.254 tell 192.168.0.12
B arp who-has 192.168.0.254 tell 192.168.0.12
...
Verrrrrrrrry Eeeeeeenteresting! I still can't ping, but tcpdump
is at least showing me more reasonable output; these actually look like
arp requests.
OK, why isn't the host replying? Let's add arp to tap0 on the
host:
ifconfig tap0 192.168.0.254 netmask 255.255.255.0 broadcast 192.168.0.255 arp up
Here's tcpdump as uml starts up:
[root@sparrow /root]# tcpdump -i tap0 -qtn
User level filter, protocol ALL, datagram packet socket
tcpdump: listening on tap0
B arp who-has 192.168.0.254 tell 192.168.0.12
> arp reply 192.168.0.254 (fe:fd:0:0:0:0) is-at fe:fd:0:0:0:0 (c0:ff:ee:c0:ff:ee)
< 192.168.0.12.2048 > 192.168.0.254.domain: udp 42 (DF)
> 192.168.0.254 > 192.168.0.12: icmp: 192.168.0.254 udp port domain unreachable (DF) [tos 0xc0]
< 192.168.0.12.2048 > 192.168.0.254.domain: udp 42 (DF)
> 192.168.0.254 > 192.168.0.12: icmp: 192.168.0.254 udp port domain unreachable (DF) [tos 0xc0]
< 192.168.0.12.2048 > 192.168.0.254.domain: udp 42 (DF)
> 192.168.0.254 > 192.168.0.12: icmp: 192.168.0.254 udp port domain unreachable (DF) [tos 0xc0]
< 192.168.0.12.2048 > 192.168.0.254.domain: udp 42 (DF)
> 192.168.0.254 > 192.168.0.12: icmp: 192.168.0.254 udp port domain unreachable (DF) [tos 0xc0]
< 192.168.0.12.2048 > 192.168.0.254.domain: udp 61 (DF)
> 192.168.0.254 > 192.168.0.12: icmp: 192.168.0.254 udp port domain unreachable (DF) [tos 0xc0]
< 192.168.0.12.2048 > 192.168.0.254.domain: udp 61 (DF)
> 192.168.0.254 > 192.168.0.12: icmp: 192.168.0.254 udp port domain unreachable (DF) [tos 0xc0]
< 192.168.0.12.2048 > 192.168.0.254.domain: udp 61 (DF)
> arp who-has 192.168.0.12 tell 192.168.0.254 (fe:fd:0:0:0:0)
< arp reply 192.168.0.12 is-at c0:ff:ee:c0:ff:ee (fe:fd:0:0:0:0)
< 192.168.0.12.2048 > 192.168.0.254.domain: udp 61 (DF)
> 192.168.0.254 > 192.168.0.12: icmp: 192.168.0.254 udp port domain unreachable (DF) [tos 0xc0]
< 192.168.0.12.2048 > 192.168.0.254.domain: udp 42 (DF)
> 192.168.0.254 > 192.168.0.12: icmp: 192.168.0.254 udp port domain unreachable (DF) [tos 0xc0]
< 192.168.0.12.2048 > 192.168.0.254.domain: udp 42 (DF)
> 192.168.0.254 > 192.168.0.12: icmp: 192.168.0.254 udp port domain unreachable (DF) [tos 0xc0]
< 192.168.0.12.2048 > 192.168.0.254.domain: udp 42 (DF)
> 192.168.0.254 > 192.168.0.12: icmp: 192.168.0.254 udp port domain unreachable (DF) [tos 0xc0]
< 192.168.0.12.2048 > 192.168.0.254.domain: udp 42 (DF)
> 192.168.0.254 > 192.168.0.12: icmp: 192.168.0.254 udp port domain unreachable (DF) [tos 0xc0]
< 192.168.0.12.2048 > 192.168.0.254.domain: udp 61 (DF)
> 192.168.0.254 > 192.168.0.12: icmp: 192.168.0.254 udp port domain unreachable (DF) [tos 0xc0]
< 192.168.0.12.2048 > 192.168.0.254.domain: udp 61 (DF)
At this point, I just have incomplete dns information; putting the
hosts IP in the uml's /etc/hosts allows the ping to proceed
correctly. Nicely enough, I can ping in and out, and even ssh in from the
outside world.
So _finally_ (:-), here are the minor issues:
- Should um_eth_net_util require a real file called /dev/tap0? If that
file is missing, should it still work?
- Could the uml's eth0 be brought up by default with the "arp" flag
set? At this point I have to run the following lines before the
networking is brought up:
/sbin/ifconfig eth0 hw ether c0:ff:ee:c0:ff:ee
/sbin/ifconfig eth0 arp
It would be cool if some random mac address could be assigned if
the user doesn't assign one and the arp flag could be set
automatically.
-----------------------------------------------------------------
Just for reference, here's the setup inside the uml:
bash# ifconfig
eth0 Link encap:Ethernet HWaddr C0:FF:EE:C0:FF:EE
inet addr:192.168.0.12 Bcast:192.168.0.255 Mask:255.255.255.0
UP BROADCAST RUNNING MULTICAST MTU:1500 Metric:1
RX packets:0 errors:0 dropped:0 overruns:0 frame:0
TX packets:57 errors:0 dropped:0 overruns:0 carrier:0
collisions:0 txqueuelen:100
Interrupt:4
bash# route -n
Kernel IP routing table
Destination Gateway Genmask Flags Metric Ref Use Iface
192.168.0.12 0.0.0.0 255.255.255.255 UH 0 0 0 eth0
192.168.0.0 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
0.0.0.0 192.168.0.254 0.0.0.0 UG 0 0 0 eth0
0.0.0.0 192.168.0.254 0.0.0.0 UG 1 0 0 eth0
Cheers,
- Bill
---------------------------------------------------------------------------
Having Microsoft give us advice on open standards is like W.C. Fields
giving moral advice to the Mormon Tabernacle Choir
-- Scott McNealy, Sun Microsystems Inc.
(Courtesy of Michael Remski <mr...@ix...>)
--------------------------------------------------------------------------
William Stearns (wst...@po...). Mason, Buildkernel, named2hosts,
and ipfwadm2ipchains are at: http://www.pobox.com/~wstearns
LinuxMonth; articles for Linux Enthusiasts! http://www.linuxmonth.com
--------------------------------------------------------------------------
|
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From: James R. L. <jl...@mi...> - 2000-09-07 22:32:01
|
On Thu, Sep 07, 2000 at 05:01:45PM -0400, William Stearns wrote: > Good day, James, Jeff, et al, > I've had some luck with the new Ethernet code, but some things > aren't working exactly as I'd expect. May I bore you with the details? > :-) > The UML is 192.168.0.12 with mac address cc0:ff:ee:c0:ff:ee, the > host is 192.168.0.254 with mac address FE:FD:00:00:00:00. Network 100 for > simplicity. > > In host, as root: > ifconfig tap0 192.168.0.254 netmask 255.255.255.0 broadcast 192.168.0.255 up > um_eth_net_util tap0 100 > Gives: > [root@sparrow /root]# um_eth_net_util tap0 100 > /dev/tap0: No such file or directory > PHY: tap0 I should probably have a more meaningful error message. /dev/tap0 is required. > Verrrrrrrrry Eeeeeeenteresting! I still can't ping, but tcpdump > is at least showing me more reasonable output; these actually look like > arp requests. > OK, why isn't the host replying? Let's add arp to tap0 on the > host: > > ifconfig tap0 192.168.0.254 netmask 255.255.255.0 broadcast 192.168.0.255 arp up Yep. Tap interfaces do not respond to arp by default. It seems like that should be a default being that it is called "ethertap" oh well. > - Should um_eth_net_util require a real file called /dev/tap0? If that > file is missing, should it still work? > > - Could the uml's eth0 be brought up by default with the "arp" flag > set? At this point I have to run the following lines before the > networking is brought up: I think the uml's ethernets have "arp" on by default. I will double check. I do know that you need to add "arp" to the tap0 interface. > It would be cool if some random mac address could be assigned if > the user doesn't assign one and the arp flag could be set > automatically. I would like to have a scheme for coming up with a unique MAC address, but I haven't yet figured one out. Any ideas? Jim -- James R. Leu |
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