Arch Linux

Hacksign

Member

Registered: 2012-07-30

Posts: 131

IPSec VPN can not access a specific ip address (network unreachable)

Hi there,

I've managed to setup an ipsec vpn server these days. After I connected to VPN server, some ip address can not be accessed.

Below is the ip allocations on server side:

root@RouterX:~# ipsec leases
Leases in pool '192.168.100.100-192.168.100.109', usage: 2/10, 2 online
  192.168.100.101   online   'node-1'
  192.168.100.100   online   'node-2'
Leases in pool '192.168.100.110-192.168.100.119', usage: 1/10, 1 online
  192.168.100.110   online   'node-3'
root@RouterX:~# ping -c 3 192.168.100.101
PING 192.168.100.101 (192.168.100.101): 56 data bytes
^C
--- 192.168.100.101 ping statistics ---
3 packets transmitted, 0 packets received, 100% packet loss
root@RouterX:~# ping -c 3 192.168.100.100
PING 192.168.100.100 (192.168.100.100): 56 data bytes
64 bytes from 192.168.100.100: seq=0 ttl=64 time=20.018 ms
64 bytes from 192.168.100.100: seq=1 ttl=64 time=20.432 ms
64 bytes from 192.168.100.100: seq=2 ttl=64 time=23.161 ms

--- 192.168.100.100 ping statistics ---
3 packets transmitted, 3 packets received, 0% packet loss
round-trip min/avg/max = 20.018/21.203/23.161 ms
root@RouterX:~# ping -c 3 192.168.100.110
PING 192.168.100.110 (192.168.100.110): 56 data bytes
64 bytes from 192.168.100.110: seq=0 ttl=64 time=481.042 ms
64 bytes from 192.168.100.110: seq=1 ttl=64 time=50.404 ms
64 bytes from 192.168.100.110: seq=2 ttl=64 time=98.258 ms

--- 192.168.100.110 ping statistics ---
3 packets transmitted, 3 packets received, 0% packet loss
round-trip min/avg/max = 50.404/209.901/481.042 ms

As you can see, node-2(192.168.100.100) & node-3(192.168.100.110) are accessable, but node-1 is not.

Node-1 & Node-2 are in same network, Node-3 is another network.

Node-1 is connected to VPN server by swanctl, Node-2 is connected to VPN server by networkmanager-strongswan plugin, Node-3 is an android device which is connected to VPN server by buld-in VPN ability.

Below is node-1's swanctl configuration:

# cat /etc/swanctl/conf.d/csj.conf 
connections {
   vpn {
       encap = yes
       mobike = yes
       version = 2
       keyingtries = 0
       dpd_delay = 30
       dpd_timeout = 90
       vips = 192.168.100.100   // this is a prefered address, but it is taken by Node-2, so this node got 192.168.100.101 address
       remote_addrs = 1.2.3.4

       local {
           auth = eap-mschapv2
           id = node-1
           eap_id = node-1
       }

       remote {
           certs = vpn-ca.pem 
           id = @xxx.com
       }

       children {
           vpn-children {
               mode = beet       // this parameter is added for test reason, and it can not effect accessability between nodes whether it exists or not.
               local_ts = 192.168.100.0/24
               remote_ts = 192.168.100.0/24,192.168.2.0/24
               start_action = start
               dpd_action = restart
               close_action = restart
           }
       }
   }
}

My question is: how to access Node1(192.168.100.101) ?

Hacksign

Member

Registered: 2012-07-30

Posts: 131

Re: IPSec VPN can not access a specific ip address (network unreachable)

And one interesting thing, after node-2 disconnected from server, I can get to node-1:

root@RouterX:~# ipsec leases
Leases in pool '192.168.100.100-192.168.100.109', usage: 2/10, 1 online
  192.168.100.101   online   'node-1'
  192.168.100.100   offline   'node-2'
Leases in pool '192.168.100.110-192.168.100.119', usage: 1/10, 1 online
  192.168.100.110   online   'node-3'
root@RouterX:~# ping 192.168.100.101
PING 192.168.100.101 (192.168.100.101): 56 data bytes
64 bytes from 192.168.100.101: seq=0 ttl=64 time=18.353 ms
64 bytes from 192.168.100.101: seq=1 ttl=64 time=18.556 ms
64 bytes from 192.168.100.101: seq=2 ttl=64 time=18.559 ms
^C
--- 192.168.100.101 ping statistics ---
3 packets transmitted, 3 packets received, 0% packet loss
round-trip min/avg/max = 18.353/18.489/18.559 ms

-----------------------Added 2024/02/16 11:10 +UTC0------------------------------------

After sniffering packages at server side with a ping command, I found the ICMP packages are forwarded to node-2 but I'm pinging node-1.

Why ipsec routing like this ?

Last edited by Hacksign (2024-02-16 11:12:47)