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Lars Kruse

2019-Jan-15 12:49 UTC

Cannot access other computers on LAN

Hello Julien,


Am Tue, 15 Jan 2019 09:30:23 +0100
schrieb Julien dupont <marcelvierzon at gmail.com>:
> In that case I see:
> IP 172.16.0.3 > 192.168.1.1: ICMP echo request, id2135, seq1, length 64
> IP 172.16.0.3 > 192.168.1.1: ICMP echo request, id2135, seq2, length 64
> IP 172.16.0.3 > 192.168.1.1: ICMP echo request, id2135, seq3, length 64
> 
> Packet goes through but no PONG back if I understand correctly. That's
> probably where it goes wrong.
Yes, the final response is missing.
But the above output also lacks the forwarded packets (into your
192.168.1.0/24 subnet).
Thus I could imagine, that at least one of the following items is true:
* "ip_forward" (/proc/sys/net/ipv4/ip_forward) is not enabled on
192.168.1.3
* firewall rules do not allow such packets to be forwarded (see the output of
  "iptables -L -vn") on 192.168.1.3

> On VPN_office 'tcdump -npi any icmp', on 192.168.1.100 'ping
172.16.0.3':
> 192.168.1.100 > 172.16.0.3: ICMP echo request, id 11452, seq1, length 64
> 192.168.1.100 > 172.16.0.3: ICMP echo request, id 11452, seq2, length 64
> 192.168.1.100 > 172.16.0.3: ICMP echo request, id 11452, seq3, length 64
> ...
This indicates, that your packets are leaving the host.
The next steps would be to check at which point they (or their response) get
lost.


Cheers,
Lars

Julien dupont

2019-Jan-15 15:33 UTC

head link

Cannot access other computers on LAN

ip_forward was not enabled, now it is. Still same result:
On VPN_office I use 'tcpdump -npi any icmp and host 192.168.1.1' and
ping
192.168.1.1 from the client:
5:28:42.646203 IP 172.16.0.3 > 192.168.1.1: ICMP echo request, id 1584, seq
1, length 64
15:28:43.663014 IP 172.16.0.3 > 192.168.1.1: ICMP echo request, id 1584,
seq 2, length 64
15:28:44.688133 IP 172.16.0.3 > 192.168.1.1: ICMP echo request, id 1584,
seq 3, length 64
15:28:45.714886 IP 172.16.0.3 > 192.168.1.1: ICMP echo request, id 1584,
seq 4, length 64
15:28:46.738332 IP 172.16.0.3 > 192.168.1.1: ICMP echo request, id 1584,
seq 5, length 64
15:28:47.756378 IP 172.16.0.3 > 192.168.1.1: ICMP echo request, id 1584,
seq 6, length 64

'iptables -L -vn' yields:

Chain INPUT (policy ACCEPT 0 packets, 0 bytes)
 pkts bytes target     prot opt in     out     source
 destination
  799  156K ACCEPT     all  --  *      *       0.0.0.0/0
0.0.0.0/0            ctstate RELATED,ESTABLISHED
    0     0 ACCEPT     all  --  lo     *       0.0.0.0/0
0.0.0.0/0
   22  1592 INPUT_direct  all  --  *      *       0.0.0.0/0
0.0.0.0/0
   22  1592 INPUT_ZONES_SOURCE  all  --  *      *       0.0.0.0/0
  0.0.0.0/0
   22  1592 INPUT_ZONES  all  --  *      *       0.0.0.0/0
0.0.0.0/0
    2   224 DROP       all  --  *      *       0.0.0.0/0
0.0.0.0/0            ctstate INVALID
   17  1140 REJECT     all  --  *      *       0.0.0.0/0
0.0.0.0/0            reject-with icmp-host-prohibited

Chain FORWARD (policy ACCEPT 0 packets, 0 bytes)
 pkts bytes target     prot opt in     out     source
 destination
    0     0 ACCEPT     all  --  *      *       0.0.0.0/0
0.0.0.0/0            ctstate RELATED,ESTABLISHED
    0     0 ACCEPT     all  --  lo     *       0.0.0.0/0
0.0.0.0/0
    0     0 FORWARD_direct  all  --  *      *       0.0.0.0/0
0.0.0.0/0
    0     0 FORWARD_IN_ZONES_SOURCE  all  --  *      *       0.0.0.0/0
      0.0.0.0/0
    0     0 FORWARD_IN_ZONES  all  --  *      *       0.0.0.0/0
0.0.0.0/0
    0     0 FORWARD_OUT_ZONES_SOURCE  all  --  *      *       0.0.0.0/0
        0.0.0.0/0
    0     0 FORWARD_OUT_ZONES  all  --  *      *       0.0.0.0/0
0.0.0.0/0
    0     0 DROP       all  --  *      *       0.0.0.0/0
0.0.0.0/0            ctstate INVALID
    0     0 REJECT     all  --  *      *       0.0.0.0/0
0.0.0.0/0            reject-with icmp-host-prohibited
    0     0 ACCEPT     all  --  VPN_Main *       0.0.0.0/0
0.0.0.0/0

Chain OUTPUT (policy ACCEPT 896 packets, 195K bytes)
 pkts bytes target     prot opt in     out     source
 destination
  898  195K OUTPUT_direct  all  --  *      *       0.0.0.0/0
0.0.0.0/0

Chain FORWARD_IN_ZONES (1 references)
 pkts bytes target     prot opt in     out     source
 destination
    0     0 FWDI_public  all  --  p8p1   *       0.0.0.0/0
0.0.0.0/0           [goto]
    0     0 FWDI_public  all  --  +      *       0.0.0.0/0
0.0.0.0/0           [goto]

Chain FORWARD_IN_ZONES_SOURCE (1 references)
 pkts bytes target     prot opt in     out     source
 destination

Chain FORWARD_OUT_ZONES (1 references)
 pkts bytes target     prot opt in     out     source
 destination
    0     0 FWDO_public  all  --  *      p8p1    0.0.0.0/0
0.0.0.0/0           [goto]
    0     0 FWDO_public  all  --  *      +       0.0.0.0/0
0.0.0.0/0           [goto]

Chain FORWARD_OUT_ZONES_SOURCE (1 references)
 pkts bytes target     prot opt in     out     source
 destination

Chain FORWARD_direct (1 references)
 pkts bytes target     prot opt in     out     source
 destination

Chain FWDI_public (2 references)
 pkts bytes target     prot opt in     out     source
 destination
    0     0 FWDI_public_log  all  --  *      *       0.0.0.0/0
0.0.0.0/0
    0     0 FWDI_public_deny  all  --  *      *       0.0.0.0/0
0.0.0.0/0
    0     0 FWDI_public_allow  all  --  *      *       0.0.0.0/0
0.0.0.0/0
    0     0 ACCEPT     icmp --  *      *       0.0.0.0/0
0.0.0.0/0

Chain FWDI_public_allow (1 references)
 pkts bytes target     prot opt in     out     source
 destination

Chain FWDI_public_deny (1 references)
 pkts bytes target     prot opt in     out     source
 destination

Chain FWDI_public_log (1 references)
 pkts bytes target     prot opt in     out     source
 destination

Chain FWDO_public (2 references)
 pkts bytes target     prot opt in     out     source
 destination
    0     0 FWDO_public_log  all  --  *      *       0.0.0.0/0
0.0.0.0/0
    0     0 FWDO_public_deny  all  --  *      *       0.0.0.0/0
0.0.0.0/0
    0     0 FWDO_public_allow  all  --  *      *       0.0.0.0/0
0.0.0.0/0

Chain FWDO_public_allow (1 references)
 pkts bytes target     prot opt in     out     source
 destination

Chain FWDO_public_deny (1 references)
 pkts bytes target     prot opt in     out     source
 destination

Chain FWDO_public_log (1 references)
 pkts bytes target     prot opt in     out     source
 destination

Chain INPUT_ZONES (1 references)
 pkts bytes target     prot opt in     out     source
 destination
   17  1140 IN_public  all  --  p8p1   *       0.0.0.0/0
0.0.0.0/0           [goto]
    5   452 IN_public  all  --  +      *       0.0.0.0/0
0.0.0.0/0           [goto]

Chain INPUT_ZONES_SOURCE (1 references)
 pkts bytes target     prot opt in     out     source
 destination

Chain INPUT_direct (1 references)
 pkts bytes target     prot opt in     out     source
 destination

Chain IN_public (2 references)
 pkts bytes target     prot opt in     out     source
 destination
   22  1592 IN_public_log  all  --  *      *       0.0.0.0/0
0.0.0.0/0
   22  1592 IN_public_deny  all  --  *      *       0.0.0.0/0
0.0.0.0/0
   22  1592 IN_public_allow  all  --  *      *       0.0.0.0/0
0.0.0.0/0
    2   168 ACCEPT     icmp --  *      *       0.0.0.0/0
0.0.0.0/0

Chain IN_public_allow (1 references)
 pkts bytes target     prot opt in     out     source
 destination
    1    60 ACCEPT     tcp  --  *      *       0.0.0.0/0
0.0.0.0/0            tcp dpt:22 ctstate NEW

Chain IN_public_deny (1 references)
 pkts bytes target     prot opt in     out     source
 destination

Chain IN_public_log (1 references)
 pkts bytes target     prot opt in     out     source
 destination

Chain OUTPUT_direct (1 references)
 pkts bytes target     prot opt in     out     source
 destination





Le mar. 15 janv. 2019 à 13:49, Lars Kruse <lists at sumpfralle.de> a écrit
:
> Hello Julien,
>
>
> Am Tue, 15 Jan 2019 09:30:23 +0100
> schrieb Julien dupont <marcelvierzon at gmail.com>:
>
> > In that case I see:
> > IP 172.16.0.3 > 192.168.1.1: ICMP echo request, id2135, seq1,
length 64
> > IP 172.16.0.3 > 192.168.1.1: ICMP echo request, id2135, seq2,
length 64
> > IP 172.16.0.3 > 192.168.1.1: ICMP echo request, id2135, seq3,
length 64
> >
> > Packet goes through but no PONG back if I understand correctly.
That's
> > probably where it goes wrong.
>
> Yes, the final response is missing.
> But the above output also lacks the forwarded packets (into your
> 192.168.1.0/24 subnet).
> Thus I could imagine, that at least one of the following items is true:
> * "ip_forward" (/proc/sys/net/ipv4/ip_forward) is not enabled on
> 192.168.1.3
> * firewall rules do not allow such packets to be forwarded (see the output
> of
>   "iptables -L -vn") on 192.168.1.3
>
>
> > On VPN_office 'tcdump -npi any icmp', on 192.168.1.100
'ping 172.16.0.3':
> > 192.168.1.100 > 172.16.0.3: ICMP echo request, id 11452, seq1,
length 64
> > 192.168.1.100 > 172.16.0.3: ICMP echo request, id 11452, seq2,
length 64
> > 192.168.1.100 > 172.16.0.3: ICMP echo request, id 11452, seq3,
length 64
> > ...
>
> This indicates, that your packets are leaving the host.
> The next steps would be to check at which point they (or their response)
> get
> lost.
>
>
> Cheers,
> Lars
> _______________________________________________
> tinc mailing list
> tinc at tinc-vpn.org
> https://www.tinc-vpn.org/cgi-bin/mailman/listinfo/tinc
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Lars Kruse

2019-Jan-15 20:09 UTC

head link

Cannot access other computers on LAN

Hello Julien,


Am Tue, 15 Jan 2019 16:33:26 +0100
schrieb Julien dupont <marcelvierzon at gmail.com>:
> ip_forward was not enabled, now it is.
a good step forward :)

(you should do this permanently via /etc/sysctl.d/)

> 'iptables -L -vn' yields:
> [..]
OK. The output tells us, that there are firewall rules.
Now you should take a look at your firewall configuration file. There you will
need to allow traffic from your tinc network into your office network. Maybe
you want to restrict this to certain IPs or ports.

As soon as your firewall rules allow forward traffic to your target, you can
check, whether these packets arrive and maybe where the response packets get
lost.

Cheers,
Lars

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