From: eubell@physik.uni-kl.de (Dieter Eubell [CIP]) Subject: ARP and SUBNETTING problems with NET-2 Date: Mon, 28 Jun 1993 21:03:02 GMT
Hello linux world!
I have two questions about subnetting and arp protocol.
1) Subnetting
The university of Kaiserslautern has a class B net (131.246.0.0) and
uses 5 bit subnetting.
The IP address of my linux box is 131.246.10.204 and the name of it is
tango.physik.uni-kl.de
The subnetmask for my computer is 255.255.248.0, the netmask is
131.246.8.0 and the broadcast address is 131.246.15.255. The default gateway is
131.246.9.5.
My rc.inet1 looks like this:
ifconfig lo 127.0.0.1
route add 127.0.0.1
ifconfig eth0 131.246.10.204 broadcast 131.246.15.255 netmask 255.255.248.0 -trailers up
route add 131.246.8.0
route add default gw 131.246.9.5 metric 1
And now the problem:
netstat -rn shows:
Destination net/address Gateway address Flags RefCnt Use Iface
default 131.246.9.5 UGN 0 0 eth0
131.246.0.0 * UN 0 0 eth0
127.0.0.1 * UH 0 0 lo
And now the question:
Why does the second route command add _131.246.0.0_ and not 131.246.8.0 ?
This is the netmask of our class B net and not my subnetmask.
2) ARP
When I enable arp debugging and ping any other host, I see many wrong ARP packets:
The output of "kd /dev/arp on" looks like this:
ARP: op REQUEST hrd = 10 Mbps Ethernet pro = 0x0800
hlen = 6 plen = 4
sender HA = 00:40:E9:D8:9F:92 PA = 131.246.10.204
target HA = FF:FF:FF:FF:FF:FF PA = 131.246.11.89
ARP: op REQUEST hrd = 10 Mbps Ethernet pro = 0x0800
hlen = 6 plen = 4
sender HA = 00:40:E9:D8:9F:92 PA = 0.64.233.216
target HA = FF:FF:FF:FF:FF:FF PA = 131.246.11.89
ARP: op REQUEST hrd = 10 Mbps Ethernet pro = 0x0800
hlen = 6 plen = 4
sender HA = 00:40:E9:D8:9F:92 PA = 131.246.10.204
target HA = FF:FF:FF:FF:FF:FF PA = 131.246.11.89
The sender PA of the second ARP debug output is completely wrong.
I can use every internet service (telnet, ftp, rsh, rlogin ....) to and from my
linux box, but our network administrator kills me because of this wrong ARP packets.
Has anybody an idea or a solution?
Please mail to eubell@physik.uni-kl.de.
PLEASE HHHEEEEEELLLLLPPPPP me. I can't use my computer in the network until the
wrong ARP packets disappear.
Thanx.