 | | | Getting DHCP, IP aliasing and IP forwarding to work together... | Getting DHCP, IP aliasing and IP forwarding to work together... 2003-11-09 - By Vladimir G. Ivanovic
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I can 't get my laptops to connect to the outside world, although they
reach their DHCP server just fine.
I 've not comprehended some facet or I must not haven 't done something
(properly), but for the life of me I don 't know what it could be.
Googling around has been helpful in getting to this point, but I 'm
missing something. Your help is appreciated.
Here 's where I am currently.
Two laptops, the DHCP server, some other machines and a DSL modem are all
connected to a 10/100 Mb Ethernet hub with the following IP addresses:
network: 64.166.134.112
netmask: 255.255.255.248
DHCPserver: 64.166.134.117 (RH9)
DSLmodem: 64.166.134.118
network: 192.168.10.0
netmask: 255.255.255.0
laptop1: 192.168.10.109 (RH9)
laptop2: 192.168.10.127 (WinXP)
I set up the DHCP server 's routing table with three commands in /etc/rc.local:
ifconfig eth0:1 192.168.10.1
route add -host 192.168.10.1 eth0:1
route add -net 192.168.10.0 netmask 255.255.255.0 eth0:1
which gives this routing table:
Destination Gateway Genmask Flags Metric Ref Use Iface
64.166.134.117 0.0.0.0 255.255.255.255 UH 0 0 0 eth0
192.168.10.1 0.0.0.0 255.255.255.255 UH 0 0 0 eth0
64.166.134.112 0.0.0.0 255.255.255.248 U 0 0 0 eth0
192.168.10.0 64.166.134.117 255.255.255.0 UG 0 0 0 eth0
169.254.0.0 0.0.0.0 255.255.0.0 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 64.166.134.118 0.0.0.0 UG 0 0 0 eth0
The DHCP server 's Ethernet network interface:
eth0 Link encap:Ethernet HWaddr 00:E0:18:05:A9:68
inet addr:64.166.134.117 Bcast:64.166.134.119 Mask:255.255.255.248
UP BROADCAST RUNNING MULTICAST MTU:1500 Metric:1
RX packets:440089 errors:0 dropped:0 overruns:0 frame:0
TX packets:409012 errors:0 dropped:0 overruns:1 carrier:0
collisions:0 txqueuelen:100
RX bytes:272871106 (260.2 Mb) TX bytes:94124015 (89.7 Mb)
Interrupt:10 Base address:0xa800 Memory:ee800000-ee800038
eth0:1 Link encap:Ethernet HWaddr 00:E0:18:05:A9:68
inet addr:192.168.10.1 Bcast:192.168.10.255 Mask:255.255.255.0
UP BROADCAST RUNNING MULTICAST MTU:1500 Metric:1
RX packets:440089 errors:0 dropped:0 overruns:0 frame:0
TX packets:409012 errors:0 dropped:0 overruns:1 carrier:0
collisions:0 txqueuelen:100
RX bytes:272871106 (260.2 Mb) TX bytes:94124015 (89.7 Mb)
Interrupt:10 Base address:0xa800 Memory:ee800000-ee800038
and IP forwarding is turned on:
# sysctl net.ipv4.ip_forward
net.ipv4.ip_forward = 1
DHCP is setup thusly (/etc/dhcpd.conf):
default-lease-time 600;
max-lease-time 7200;
option subnet-mask 255.255.255.0;
option broadcast-address 192.168.10.255;
option routers 192.168.10.1;
option domain-name-servers 64.166.134.117, 206.13.12.28, 206.13.31.12;
option domain-name "leonora.org ";
ddns-update-style ad-hoc;
subnet 192.168.10.0 netmask 255.255.255.0 {
range 192.168.10.2 192.168.10.254;
host laptop1 {
hardware ethernet 00:0b:db:1b:ca:5a;
fixed-address 192.168.10.109;
}
host laptop2 {
hardware ethernet 00:10:a4:03:dc:45;
fixed-address 192.168.10.127;
}
}
I 've entered the necessary mumbo-jumbo for iptables to work with my new
eth0:1 interface, but I get the same behavior (no access from laptops
to the Internet) even if I turn iptables off.
Concentrating on laptop1, the Linux laptop, for the moment... The last
entry in laptop1 's dhcp lease looks like this:
lease {
interface "eth0 ";
fixed-address 192.168.10.109;
option subnet-mask 255.255.255.0;
option routers 192.168.10.1;
option dhcp-lease-time 600;
option dhcp-message-type 5;
option domain-name-servers 64.166.134.117,206.13.12.28,206.13.31.12;
option dhcp-server-identifier 64.166.134.117;
option broadcast-address 192.168.10.255;
option domain-name "leonora.org ";
renew 0 2003/11/9 19:22:16;
rebind 0 2003/11/9 19:26:27;
expire 0 2003/11/9 19:27:42;
}
Its Ethernet interface is:
eth0 Link encap:Ethernet HWaddr 00:0B:DB:1B:CA:5A
inet addr:192.168.10.109 Bcast:192.168.10.255 Mask:255.255.255.0
UP BROADCAST RUNNING MULTICAST MTU:1500 Metric:1
RX packets:128741 errors:0 dropped:0 overruns:0 frame:0
TX packets:228979 errors:0 dropped:0 overruns:0 carrier:2
collisions:0 txqueuelen:100
RX bytes:10101993 (9.6 Mb) TX bytes:287682017 (274.3 Mb)
Interrupt:10 Memory:e0100000-e0101080
and its routing table is:
Destination Gateway Genmask Flags Metric Ref Use Iface
192.168.10.0 0.0.0.0 255.255.255.0 U 0 0 0 eth0
169.254.0.0 0.0.0.0 255.255.0.0 U 0 0 0 eth0
127.0.0.0 0.0.0.0 255.0.0.0 U 0 0 0 lo
0.0.0.0 192.168.10.1 0.0.0.0 UG 0 0 0 eth0
Hmmm. no host entry, but adding one with
route add -host 192.168.10.109 eth0
didn 't change any behavior I could detect.
So, everything looks OK to me and I 've exhausted my knowledge. Any suggestions?
--- Vladimir
-- ---- ---- ---- ---- ---- ---- ---- ---- ---- ---- ---- ---- ---- ----
Vladimir G. Ivanovic
http://leonora.org/~vladimir
2770 Cowper St. vladimir@(protected)
Palo Alto, CA 94306-2447 +1 650 678 8014
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