I had this configuration before, and it used to work well, but now I
got a new server and I can't setup it to share the internet connection
from ppp0.
The client connects directly on eth0 through a dhcp server, and it can
get an IP just fine. The problem seems only to appear when I set this
rule:
`iptables -t nat -A POSTROUTING -o ppp0 -j MASQUERADE`
Just after that, the client won't be able to receive an IP from the
server anymore. Here's the configuration files:
The /etc/dhcp/dhcpd.conf file:
---
ddns-update-style none;
default-lease-time 600;
max-lease-time 7200;
log-facility local7;
subnet 192.168.0.0 netmask 255.255.255.0 {
option routers 192.168.0.1;
option domain-name "onix";
range 192.168.0.2 192.168.0.10;
option domain-name-servers 201.10.120.2, 201.10.128.2;
option broadcast-address 192.168.0.1;
option ip-forwarding on;
}
---
The connection script:
---
#!/bin/bash
/sbin/ifconfig eth0 192.168.0.1 netmask 255.255.255.0 broadcast 192.168.0.1
/etc/init.d/isc-dhcp-server stop
/etc/init.d/isc-dhcp-server start
iptables -F
iptables -t nat -F
iptables -t mangle -F
iptables -X
iptables -A INPUT -i lo -j ACCEPT
iptables -A INPUT -m state --state ESTABLISHED,RELATED -j ACCEPT
iptables -A FORWARD -i ppp0 -o eth0 -m state --state
ESTABLISHED,RELATED -j ACCEPT
iptables -A FORWARD -i eth0 -o ppp0 -j ACCEPT
iptables -t nat -A POSTROUTING -o ppp0 -j MASQUERADE
iptables -A FORWARD -i ppp0 -o ppp0 -j REJECT
echo 1 > /proc/sys/net/ipv4/ip_forward
---
After the problem appears I ran tcpdump on both eth interfaces of
client and server while the client send DHCPDISCOVER:
Client tcpdump:
---
listening on eth0, link-type EN10MB (Ethernet), capture size 65535 bytes
17:32:10.848029 IP 0.0.0.0.bootpc > 255.255.255.255.bootps:
BOOTP/DHCP, Request from 00:16:36:96:2b:15 (oui Unknown), length 300
17:32:16.000175 IP 0.0.0.0.bootpc > 255.255.255.255.bootps:
BOOTP/DHCP, Request from 00:16:36:96:2b:15 (oui Unknown), length 300
17:32:30.004579 IP 0.0.0.0.bootpc > 255.255.255.255.bootps:
BOOTP/DHCP, Request from 00:16:36:96:2b:15 (oui Unknown), length 300
17:32:37.005508 IP 0.0.0.0.bootpc > 255.255.255.255.bootps:
BOOTP/DHCP, Request from 00:16:36:96:2b:15 (oui Unknown), length 300
17:32:49.007886 IP 0.0.0.0.bootpc > 255.255.255.255.bootps:
BOOTP/DHCP, Request from 00:16:36:96:2b:15 (oui Unknown), length 300
17:32:56.000168 IP 0.0.0.0.bootpc > 255.255.255.255.bootps:
BOOTP/DHCP, Request from 00:16:36:96:2b:15 (oui Unknown), length 300
^C
6 packets captured
6 packets received by filter
0 packets dropped by kernel
---
Server tcpdump:
---
listening on eth0, link-type EN10MB (Ethernet), capture size 65535 bytes
17:32:10.533386 IP 0.0.0.0.bootpc > 255.255.255.255.bootps:
BOOTP/DHCP, Request from 00:16:36:96:2b:15 (oui Unknown), length 300
17:32:10.536878 ARP, Request who-has 192.168.0.2 tell onix.local, length 28
17:32:10.634525 IP6 fe80::f24d:a2ff:fed9:35c.mdns > ff02::fb.mdns: 0
PTR (QM)? 255.255.255.255.in-addr.arpa. (46)
17:32:10.634596 IP onix.local.mdns > 224.0.0.251.mdns: 0 PTR (QM)?
255.255.255.255.in-addr.arpa. (46)
17:32:11.000641 IP onix.local.bootps > 192.168.0.2.bootpc: BOOTP/DHCP,
Reply, length 300
17:32:11.535919 ARP, Request who-has 192.168.0.2 tell onix.local, length 28
17:32:11.635959 IP6 fe80::f24d:a2ff:fed9:35c.mdns > ff02::fb.mdns: 0
PTR (QM)? 255.255.255.255.in-addr.arpa. (46)
17:32:11.636049 IP onix.local.mdns > 224.0.0.251.mdns: 0 PTR (QM)?
255.255.255.255.in-addr.arpa. (46)
17:32:12.535882 ARP, Request who-has 192.168.0.2 tell onix.local, length 28
17:32:13.638404 IP6 fe80::f24d:a2ff:fed9:35c.mdns > ff02::fb.mdns: 0
PTR (QM)? 255.255.255.255.in-addr.arpa. (46)
17:32:13.638488 IP onix.local.mdns > 224.0.0.251.mdns: 0 PTR (QM)?
255.255.255.255.in-addr.arpa. (46)
17:32:15.636359 IP6 fe80::f24d:a2ff:fed9:35c.mdns > ff02::fb.mdns: 0
PTR (QM)? 0.0.0.0.in-addr.arpa. (38)
17:32:15.636444 IP onix.local.mdns > 224.0.0.251.mdns: 0 PTR (QM)?
0.0.0.0.in-addr.arpa. (38)
17:32:15.685847 IP 0.0.0.0.bootpc > 255.255.255.255.bootps:
BOOTP/DHCP, Request from 00:16:36:96:2b:15 (oui Unknown), length 300
17:32:15.686038 IP onix.local.bootps > 192.168.0.2.bootpc: BOOTP/DHCP,
Reply, length 300
17:32:16.637294 IP6 fe80::f24d:a2ff:fed9:35c.mdns > ff02::fb.mdns: 0
PTR (QM)? 0.0.0.0.in-addr.arpa. (38)
17:32:16.637362 IP onix.local.mdns > 224.0.0.251.mdns: 0 PTR (QM)?
0.0.0.0.in-addr.arpa. (38)
17:32:18.638762 IP6 fe80::f24d:a2ff:fed9:35c.mdns > ff02::fb.mdns: 0
PTR (QM)? 0.0.0.0.in-addr.arpa. (38)
17:32:18.638856 IP onix.local.mdns > 224.0.0.251.mdns: 0 PTR (QM)?
0.0.0.0.in-addr.arpa. (38)
17:32:20.639711 IP6 fe80::f24d:a2ff:fed9:35c.mdns > ff02::fb.mdns: 0
PTR (QM)? 2.0.168.192.in-addr.arpa. (42)
17:32:20.639797 IP onix.local.mdns > 224.0.0.251.mdns: 0 PTR (QM)?
2.0.168.192.in-addr.arpa. (42)
17:32:21.641098 IP6 fe80::f24d:a2ff:fed9:35c.mdns > ff02::fb.mdns: 0
PTR (QM)? 2.0.168.192.in-addr.arpa. (42)
17:32:21.641193 IP onix.local.mdns > 224.0.0.251.mdns: 0 PTR (QM)?
2.0.168.192.in-addr.arpa. (42)
17:32:23.642208 IP6 fe80::f24d:a2ff:fed9:35c.mdns > ff02::fb.mdns: 0
PTR (QM)? 2.0.168.192.in-addr.arpa. (42)
17:32:23.642301 IP onix.local.mdns > 224.0.0.251.mdns: 0 PTR (QM)?
2.0.168.192.in-addr.arpa. (42)
17:32:25.642116 IP6 fe80::f24d:a2ff:fed9:35c.mdns > ff02::fb.mdns: 0
PTR (QM)? 1.0.168.192.in-addr.arpa. (42)
17:32:25.642198 IP onix.local.mdns > 224.0.0.251.mdns: 0 PTR (QM)?
1.0.168.192.in-addr.arpa. (42)
17:32:25.642272 IP onix.local.mdns > 224.0.0.251.mdns: 0*- [0q] 1/0/0
(Cache flush) PTR onix.local. (60)
17:32:25.743060 IP6 fe80::f24d:a2ff:fed9:35c.mdns > ff02::fb.mdns: 0
PTR (QM)? 251.0.0.224.in-addr.arpa. (42)
17:32:25.743136 IP onix.local.mdns > 224.0.0.251.mdns: 0 PTR (QM)?
251.0.0.224.in-addr.arpa. (42)
17:32:26.743316 IP6 fe80::f24d:a2ff:fed9:35c.mdns > ff02::fb.mdns: 0
PTR (QM)? 251.0.0.224.in-addr.arpa. (42)
17:32:26.743409 IP onix.local.mdns > 224.0.0.251.mdns: 0 PTR (QM)?
251.0.0.224.in-addr.arpa. (42)
17:32:28.744853 IP6 fe80::f24d:a2ff:fed9:35c.mdns > ff02::fb.mdns: 0
PTR (QM)? 251.0.0.224.in-addr.arpa. (42)
17:32:28.744955 IP onix.local.mdns > 224.0.0.251.mdns: 0 PTR (QM)?
251.0.0.224.in-addr.arpa. (42)
17:32:36.692468 IP 0.0.0.0.bootpc > 255.255.255.255.bootps:
BOOTP/DHCP, Request from 00:16:36:96:2b:15 (oui Unknown), length 300
17:32:36.692678 IP onix.local.bootps > 192.168.0.2.bootpc: BOOTP/DHCP,
Reply, length 300
17:32:48.695611 IP 0.0.0.0.bootpc > 255.255.255.255.bootps:
BOOTP/DHCP, Request from 00:16:36:96:2b:15 (oui Unknown), length 300
17:32:48.695863 IP onix.local.bootps > 192.168.0.2.bootpc: BOOTP/DHCP,
Reply, length 300
17:32:55.688296 IP 0.0.0.0.bootpc > 255.255.255.255.bootps:
BOOTP/DHCP, Request from 00:16:36:96:2b:15 (oui Unknown), length 300
17:32:55.688546 IP onix.local.bootps > 192.168.0.2.bootpc: BOOTP/DHCP,
Reply, length 300
^C
40 packets captured
42 packets received by filter
2 packets dropped by kernel
---
Please let me knot about any other info that I can provide.
Thanks.
--
Vinicius Massuchetto
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