Ho un box Debian che sto cercando di configurare come router e un box Ubuntu che sto usando come client.
Il mio problema è che quando il client Ubuntu tenta di eseguire il ping di un server su Internet, tutti i pacchetti vengono persi (anche se, come puoi vedere di seguito, sembrano andare sul server e tornare indietro senza problemi).
Lo sto facendo nella Ubuntu Box:
# ping -I eth1 my.remote-server.com
PING my.remote-server.com (X.X.X.X) from 10.1.1.12 eth1: 56(84) bytes of data.
^C
--- my.remote-server.com ping statistics ---
13 packets transmitted, 0 received, 100% packet loss, time 12094ms
(Ho cambiato il nome e l'IP del server remoto per la privacy).
Dal router Debian vedo questo:
# tcpdump -i eth1 -qtln icmp
tcpdump: verbose output suppressed, use -v or -vv for full protocol decode
listening on eth1, link-type EN10MB (Ethernet), capture size 65535 bytes
IP X.X.X.X > 10.1.1.12: ICMP echo reply, id 305, seq 7, length 64
IP 10.1.1.12 > X.X.X.X: ICMP echo request, id 305, seq 8, length 64
IP X.X.X.X > 10.1.1.12: ICMP echo reply, id 305, seq 8, length 64
IP 10.1.1.12 > X.X.X.X: ICMP echo request, id 305, seq 9, length 64
IP X.X.X.X > 10.1.1.12: ICMP echo reply, id 305, seq 9, length 64
IP 10.1.1.12 > X.X.X.X: ICMP echo request, id 305, seq 10, length 64
IP X.X.X.X > 10.1.1.12: ICMP echo reply, id 305, seq 10, length 64
IP 10.1.1.12 > X.X.X.X: ICMP echo request, id 305, seq 11, length 64
IP X.X.X.X > 10.1.1.12: ICMP echo reply, id 305, seq 11, length 64
^C
9 packets captured
9 packets received by filter
0 packets dropped by kernel
# tcpdump -i eth2 -qtln icmp
tcpdump: verbose output suppressed, use -v or -vv for full protocol decode
listening on eth2, link-type EN10MB (Ethernet), capture size 65535 bytes
IP 192.168.1.10 > X.X.X.X: ICMP echo request, id 360, seq 213, length 64
IP X.X.X.X > 192.168.1.10: ICMP echo reply, id 360, seq 213, length 64
IP 192.168.1.10 > X.X.X.X: ICMP echo request, id 360, seq 214, length 64
IP X.X.X.X > 192.168.1.10: ICMP echo reply, id 360, seq 214, length 64
IP 192.168.1.10 > X.X.X.X: ICMP echo request, id 360, seq 215, length 64
IP X.X.X.X > 192.168.1.10: ICMP echo reply, id 360, seq 215, length 64
IP 192.168.1.10 > X.X.X.X: ICMP echo request, id 360, seq 216, length 64
IP X.X.X.X > 192.168.1.10: ICMP echo reply, id 360, seq 216, length 64
IP 192.168.1.10 > X.X.X.X: ICMP echo request, id 360, seq 217, length 64
IP X.X.X.X > 192.168.1.10: ICMP echo reply, id 360, seq 217, length 64
^C
10 packets captured
10 packets received by filter
0 packets dropped by kernel
E sul server remoto vedo questo:
# tcpdump -i eth0 -qtln icmp
tcpdump: verbose output suppressed, use -v or -vv for full protocol decode
listening on eth0, link-type EN10MB (Ethernet), capture size 96 bytes
IP Y.Y.Y.Y > X.X.X.X: ICMP echo request, id 360, seq 1, length 64
IP X.X.X.X > Y.Y.Y.Y: ICMP echo reply, id 360, seq 1, length 64
IP Y.Y.Y.Y > X.X.X.X: ICMP echo request, id 360, seq 2, length 64
IP X.X.X.X > Y.Y.Y.Y: ICMP echo reply, id 360, seq 2, length 64
IP Y.Y.Y.Y > X.X.X.X: ICMP echo request, id 360, seq 3, length 64
IP X.X.X.X > Y.Y.Y.Y: ICMP echo reply, id 360, seq 3, length 64
IP Y.Y.Y.Y > X.X.X.X: ICMP echo request, id 360, seq 4, length 64
IP X.X.X.X > Y.Y.Y.Y: ICMP echo reply, id 360, seq 4, length 64
IP Y.Y.Y.Y > X.X.X.X: ICMP echo request, id 360, seq 5, length 64
IP X.X.X.X > Y.Y.Y.Y: ICMP echo reply, id 360, seq 5, length 64
IP Y.Y.Y.Y > X.X.X.X: ICMP echo request, id 360, seq 6, length 64
IP X.X.X.X > Y.Y.Y.Y: ICMP echo reply, id 360, seq 6, length 64
IP Y.Y.Y.Y > X.X.X.X: ICMP echo request, id 360, seq 7, length 64
IP X.X.X.X > Y.Y.Y.Y: ICMP echo reply, id 360, seq 7, length 64
IP Y.Y.Y.Y > X.X.X.X: ICMP echo request, id 360, seq 8, length 64
IP X.X.X.X > Y.Y.Y.Y: ICMP echo reply, id 360, seq 8, length 64
IP Y.Y.Y.Y > X.X.X.X: ICMP echo request, id 360, seq 9, length 64
IP X.X.X.X > Y.Y.Y.Y: ICMP echo reply, id 360, seq 9, length 64
18 packets captured
228 packets received by filter
92 packets dropped by kernel
Qui "XXXX" è l'IP del mio server remoto e "YYYY" è l'IP pubblico della mia rete locale. Quindi, quello che capisco è che i pacchetti ping stanno uscendo dalla scatola di Ubuntu (10.1.1.12), al router (10.1.1.1), da lì al router successivo (192.168.1.1) e raggiungendo il server remoto (XXXX ). Quindi tornano fino al router Debian, ma non raggiungono mai la casella Ubuntu.
Cosa mi sto perdendo?
Ecco la configurazione del router Debian:
# ifconfig
eth1 Link encap:Ethernet HWaddr 94:0c:6d:82:0d:98
inet addr:10.1.1.1 Bcast:10.1.1.255 Mask:255.255.255.0
inet6 addr: fe80::960c:6dff:fe82:d98/64 Scope:Link
UP BROADCAST RUNNING MULTICAST MTU:1500 Metric:1
RX packets:105761 errors:0 dropped:0 overruns:0 frame:0
TX packets:48944 errors:0 dropped:0 overruns:0 carrier:0
collisions:0 txqueuelen:1000
RX bytes:40298768 (38.4 MiB) TX bytes:44831595 (42.7 MiB)
Interrupt:19 Base address:0x6000
eth2 Link encap:Ethernet HWaddr 6c:f0:49:a4:47:38
inet addr:192.168.1.10 Bcast:192.168.1.255 Mask:255.255.255.0
inet6 addr: fe80::6ef0:49ff:fea4:4738/64 Scope:Link
UP BROADCAST RUNNING MULTICAST MTU:1500 Metric:1
RX packets:38335992 errors:0 dropped:0 overruns:0 frame:0
TX packets:37097705 errors:0 dropped:0 overruns:0 carrier:1
collisions:0 txqueuelen:1000
RX bytes:4260680226 (3.9 GiB) TX bytes:3759806551 (3.5 GiB)
Interrupt:27
eth3 Link encap:Ethernet HWaddr 94:0c:6d:82:c8:72
UP BROADCAST MULTICAST MTU:1500 Metric:1
RX packets:0 errors:0 dropped:0 overruns:0 frame:0
TX packets:0 errors:0 dropped:0 overruns:0 carrier:0
collisions:0 txqueuelen:1000
RX bytes:0 (0.0 B) TX bytes:0 (0.0 B)
Interrupt:20 Base address:0x2000
lo Link encap:Local Loopback
inet addr:127.0.0.1 Mask:255.0.0.0
inet6 addr: ::1/128 Scope:Host
UP LOOPBACK RUNNING MTU:16436 Metric:1
RX packets:3408 errors:0 dropped:0 overruns:0 frame:0
TX packets:3408 errors:0 dropped:0 overruns:0 carrier:0
collisions:0 txqueuelen:0
RX bytes:358445 (350.0 KiB) TX bytes:358445 (350.0 KiB)
tun0 Link encap:UNSPEC HWaddr 00-00-00-00-00-00-00-00-00-00-00-00-00-00-00-00
inet addr:10.8.0.1 P-t-P:10.8.0.2 Mask:255.255.255.255
UP POINTOPOINT RUNNING NOARP MULTICAST MTU:1500 Metric:1
RX packets:2767779 errors:0 dropped:0 overruns:0 frame:0
TX packets:1569477 errors:0 dropped:0 overruns:0 carrier:0
collisions:0 txqueuelen:100
RX bytes:3609469393 (3.3 GiB) TX bytes:96113978 (91.6 MiB)
# route -n
Kernel IP routing table
Destination Gateway Genmask Flags Metric Ref Use Iface
10.8.0.2 0.0.0.0 255.255.255.255 UH 0 0 0 tun0
127.0.0.1 0.0.0.0 255.255.255.255 UH 0 0 0 lo
10.8.0.0 10.8.0.2 255.255.255.0 UG 0 0 0 tun0
192.168.1.0 0.0.0.0 255.255.255.0 U 1 0 0 eth2
10.1.1.0 0.0.0.0 255.255.255.0 U 0 0 0 eth1
0.0.0.0 192.168.1.1 0.0.0.0 UG 0 0 0 eth2
# arp -n
# Note: Here I have changed all the different MACs except the ones corresponding to the Ubuntu box (on 10.1.1.12 and 192.168.1.12)
Address HWtype HWaddress Flags Mask Iface
192.168.1.118 ether NN:NN:NN:NN:NN:NN C eth2
192.168.1.72 ether NN:NN:NN:NN:NN:NN C eth2
192.168.1.94 ether NN:NN:NN:NN:NN:NN C eth2
192.168.1.102 ether NN:NN:NN:NN:NN:NN C eth2
10.1.1.12 ether 00:1e:67:15:2b:f0 C eth1
192.168.1.86 ether NN:NN:NN:NN:NN:NN C eth2
192.168.1.2 ether NN:NN:NN:NN:NN:NN C eth2
192.168.1.61 ether NN:NN:NN:NN:NN:NN C eth2
192.168.1.64 ether NN:NN:NN:NN:NN:NN C eth2
192.168.1.116 ether NN:NN:NN:NN:NN:NN C eth2
192.168.1.91 ether NN:NN:NN:NN:NN:NN C eth2
192.168.1.52 ether NN:NN:NN:NN:NN:NN C eth2
192.168.1.93 ether NN:NN:NN:NN:NN:NN C eth2
192.168.1.87 ether NN:NN:NN:NN:NN:NN C eth2
192.168.1.92 ether NN:NN:NN:NN:NN:NN C eth2
192.168.1.100 ether NN:NN:NN:NN:NN:NN C eth2
192.168.1.40 ether NN:NN:NN:NN:NN:NN C eth2
192.168.1.53 ether NN:NN:NN:NN:NN:NN C eth2
192.168.1.1 ether NN:NN:NN:NN:NN:NN C eth2
192.168.1.83 ether NN:NN:NN:NN:NN:NN C eth2
192.168.1.89 ether NN:NN:NN:NN:NN:NN C eth2
192.168.1.12 ether 00:1e:67:15:2b:f1 C eth2
192.168.1.77 ether NN:NN:NN:NN:NN:NN C eth2
192.168.1.66 ether NN:NN:NN:NN:NN:NN C eth2
192.168.1.90 ether NN:NN:NN:NN:NN:NN C eth2
192.168.1.65 ether NN:NN:NN:NN:NN:NN C eth2
192.168.1.41 ether NN:NN:NN:NN:NN:NN C eth2
192.168.1.78 ether NN:NN:NN:NN:NN:NN C eth2
192.168.1.123 ether NN:NN:NN:NN:NN:NN C eth2
# iptables -L -n
Chain INPUT (policy ACCEPT)
target prot opt source destination
Chain FORWARD (policy ACCEPT)
target prot opt source destination
Chain OUTPUT (policy ACCEPT)
target prot opt source destination
# iptables -L -n -t nat
Chain PREROUTING (policy ACCEPT)
target prot opt source destination
Chain POSTROUTING (policy ACCEPT)
target prot opt source destination
MASQUERADE all -- 10.1.1.0/24 !10.1.1.0/24
MASQUERADE all -- !10.1.1.0/24 10.1.1.0/24
Chain OUTPUT (policy ACCEPT)
target prot opt source destination
Ed ecco la scatola di Ubuntu:
# ifconfig
eth0 Link encap:Ethernet HWaddr 00:1e:67:15:2b:f1
inet addr:192.168.1.12 Bcast:192.168.1.255 Mask:255.255.255.0
inet6 addr: fe80::21e:67ff:fe15:2bf1/64 Scope:Link
UP BROADCAST RUNNING MULTICAST MTU:1500 Metric:1
RX packets:28785139 errors:0 dropped:0 overruns:0 frame:0
TX packets:19050735 errors:0 dropped:0 overruns:0 carrier:0
collisions:0 txqueuelen:1000
RX bytes:32068182803 (32.0 GB) TX bytes:6061333280 (6.0 GB)
Interrupt:16 Memory:b1a00000-b1a20000
eth1 Link encap:Ethernet HWaddr 00:1e:67:15:2b:f0
inet addr:10.1.1.12 Bcast:10.1.1.255 Mask:255.255.255.0
inet6 addr: fe80::21e:67ff:fe15:2bf0/64 Scope:Link
UP BROADCAST RUNNING MULTICAST MTU:1500 Metric:1
RX packets:285086 errors:0 dropped:0 overruns:0 frame:0
TX packets:12719 errors:0 dropped:0 overruns:0 carrier:0
collisions:0 txqueuelen:1000
RX bytes:30817249 (30.8 MB) TX bytes:2153228 (2.1 MB)
Interrupt:16 Memory:b1900000-b1920000
lo Link encap:Local Loopback
inet addr:127.0.0.1 Mask:255.0.0.0
inet6 addr: ::1/128 Scope:Host
UP LOOPBACK RUNNING MTU:16436 Metric:1
RX packets:86048 errors:0 dropped:0 overruns:0 frame:0
TX packets:86048 errors:0 dropped:0 overruns:0 carrier:0
collisions:0 txqueuelen:0
RX bytes:11426538 (11.4 MB) TX bytes:11426538 (11.4 MB)
# route -n
Kernel IP routing table
Destination Gateway Genmask Flags Metric Ref Use Iface
0.0.0.0 192.168.1.1 0.0.0.0 UG 0 0 0 eth0
0.0.0.0 10.1.1.1 0.0.0.0 UG 100 0 0 eth1
10.1.1.0 0.0.0.0 255.255.255.0 U 0 0 0 eth1
10.8.0.0 192.168.1.10 255.255.255.0 UG 0 0 0 eth0
169.254.0.0 0.0.0.0 255.255.0.0 U 1000 0 0 eth0
192.168.1.0 0.0.0.0 255.255.255.0 U 1 0 0 eth0
# arp -n
# Note: Here I have changed all the different MACs except the ones corresponding to the Debian box (on 10.1.1.1 and 192.168.1.10)
Address HWtype HWaddress Flags Mask Iface
192.168.1.70 ether NN:NN:NN:NN:NN:NN C eth0
192.168.1.90 ether NN:NN:NN:NN:NN:NN C eth0
192.168.1.97 ether NN:NN:NN:NN:NN:NN C eth0
192.168.1.103 ether NN:NN:NN:NN:NN:NN C eth0
192.168.1.13 ether NN:NN:NN:NN:NN:NN C eth0
192.168.1.120 (incomplete) eth0
192.168.1.111 ether NN:NN:NN:NN:NN:NN C eth0
192.168.1.118 ether NN:NN:NN:NN:NN:NN C eth0
192.168.1.51 ether NN:NN:NN:NN:NN:NN C eth0
192.168.1.102 (incomplete) eth0
192.168.1.64 ether NN:NN:NN:NN:NN:NN C eth0
192.168.1.52 ether NN:NN:NN:NN:NN:NN C eth0
192.168.1.74 (incomplete) eth0
192.168.1.94 ether NN:NN:NN:NN:NN:NN C eth0
192.168.1.121 ether NN:NN:NN:NN:NN:NN C eth0
192.168.1.72 ether NN:NN:NN:NN:NN:NN C eth0
192.168.1.87 ether NN:NN:NN:NN:NN:NN C eth0
192.168.1.91 ether NN:NN:NN:NN:NN:NN C eth0
192.168.1.71 ether NN:NN:NN:NN:NN:NN C eth0
192.168.1.78 ether NN:NN:NN:NN:NN:NN C eth0
192.168.1.83 ether NN:NN:NN:NN:NN:NN C eth0
192.168.1.88 (incomplete) eth0
192.168.1.82 ether NN:NN:NN:NN:NN:NN C eth0
192.168.1.98 ether NN:NN:NN:NN:NN:NN C eth0
192.168.1.100 ether NN:NN:NN:NN:NN:NN C eth0
192.168.1.93 ether NN:NN:NN:NN:NN:NN C eth0
192.168.1.73 ether NN:NN:NN:NN:NN:NN C eth0
192.168.1.11 ether NN:NN:NN:NN:NN:NN C eth0
192.168.1.85 (incomplete) eth0
192.168.1.112 ether NN:NN:NN:NN:NN:NN C eth0
192.168.1.89 ether NN:NN:NN:NN:NN:NN C eth0
192.168.1.65 ether NN:NN:NN:NN:NN:NN C eth0
192.168.1.81 ether NN:NN:NN:NN:NN:NN C eth0
10.1.1.1 ether 94:0c:6d:82:0d:98 C eth1
192.168.1.53 ether NN:NN:NN:NN:NN:NN C eth0
192.168.1.116 ether NN:NN:NN:NN:NN:NN C eth0
192.168.1.61 ether NN:NN:NN:NN:NN:NN C eth0
192.168.1.10 ether 6c:f0:49:a4:47:38 C eth0
192.168.1.86 (incomplete) eth0
192.168.1.119 ether NN:NN:NN:NN:NN:NN C eth0
192.168.1.66 ether NN:NN:NN:NN:NN:NN C eth0
192.168.1.1 ether NN:NN:NN:NN:NN:NN C eth0
192.168.1.1 ether NN:NN:NN:NN:NN:NN C eth1
192.168.1.92 ether NN:NN:NN:NN:NN:NN C eth0
# iptables -L -n
Chain INPUT (policy ACCEPT)
target prot opt source destination
Chain FORWARD (policy ACCEPT)
target prot opt source destination
Chain OUTPUT (policy ACCEPT)
target prot opt source destination
# iptables -L -n -t nat
Chain PREROUTING (policy ACCEPT)
target prot opt source destination
Chain INPUT (policy ACCEPT)
target prot opt source destination
Chain OUTPUT (policy ACCEPT)
target prot opt source destination
Chain POSTROUTING (policy ACCEPT)
target prot opt source destination
Modifica: seguendo il suggerimento di Patrick, ho fatto un tcpdump con la casella Ubuntu e vedo questo:
# tcpdump -i eth1 -qtln icmp
tcpdump: verbose output suppressed, use -v or -vv for full protocol decode
listening on eth1, link-type EN10MB (Ethernet), capture size 65535 bytes
IP 10.1.1.12 > X.X.X.X: ICMP echo request, id 21967, seq 1, length 64
IP X.X.X.X > 10.1.1.12: ICMP echo reply, id 21967, seq 1, length 64
IP 10.1.1.12 > X.X.X.X: ICMP echo request, id 21967, seq 2, length 64
IP X.X.X.X > 10.1.1.12: ICMP echo reply, id 21967, seq 2, length 64
IP 10.1.1.12 > X.X.X.X: ICMP echo request, id 21967, seq 3, length 64
IP X.X.X.X > 10.1.1.12: ICMP echo reply, id 21967, seq 3, length 64
IP 10.1.1.12 > X.X.X.X: ICMP echo request, id 21967, seq 4, length 64
IP X.X.X.X > 10.1.1.12: ICMP echo reply, id 21967, seq 4, length 64
IP 10.1.1.12 > X.X.X.X: ICMP echo request, id 21967, seq 5, length 64
IP X.X.X.X > 10.1.1.12: ICMP echo reply, id 21967, seq 5, length 64
IP 10.1.1.12 > X.X.X.X: ICMP echo request, id 21967, seq 6, length 64
IP X.X.X.X > 10.1.1.12: ICMP echo reply, id 21967, seq 6, length 64
^C
12 packets captured
12 packets received by filter
0 packets dropped by kernel
Quindi la domanda è: se tutti i pacchetti sembrano andare e venire, perché il ping segnala una perdita di pacchetti del 100%?
iptables -L -n
per il router Debian. È vuoto.
MASQUERADE all -- 10.1.1.0/24 !10.1.1.0/24
MASQUERADE all -- !10.1.1.0/24 10.1.1.0/24