pinging same host on the internet from two different LAN stations

[Melameth, Daniel D.]

Daniel Hartmeier wrote:
> On Tue, Jul 26, 2005 at 05:58:18AM -0700, Pejman Moghadam wrote:
> > I have one FreeBSD 5.4 router/firewall box in my LAN that do NAT
> > with PF. 
> > The problem is I can't ping the same machine on the internet from
> > two or more different machines on my LAN at the same time. only one
> > of my LAN clients can ping that target, and pinging that target
> > from another station is possible only when i stop pinging from
> > first client.  
> > Is there any way or any tool that ICMP portmapping allows
> > simultaneous connections to external targets from multiple machines
> > from the LAN? 
> 
> I don't believe you have actually tried this.
> 
> From one workstation (10.1.1.20)
> 
>   $ ping 199.185.137.3
>   64 bytes from 199.185.137.3: icmp_seq=0 ttl=235 time=218.693 ms
>   64 bytes from 199.185.137.3: icmp_seq=1 ttl=235 time=211.615 ms
>   [...]
> 
> At the same time, from another workstation (10.2.2.11)
> 
>   $ ping 199.185.137.3
>   64 bytes from 199.185.137.3: icmp_seq=0 ttl=235 time=195.604 ms
>   64 bytes from 199.185.137.3: icmp_seq=1 ttl=235 time=194.387 ms
> 
> On the gateway which does NAT for both
> 
>   # pfctl -ss | grep icmp
>   kue0 icmp 10.1.1.20:354 -> 62.65.145.30:354 -> 199.185.137.3:354 0:0
>   kue0 icmp 10.2.2.11:19057 -> 62.65.145.30:19057 ->
> 199.185.137.3:19057 0:0 
> 
> What looks like port numbers in the state is the ICMP ID, a number
> chosen randomly for one ping invokation. pf uses this to dispatch
> incoming replies from the external host to the appropriate internal
> host.

FWIW, while I haven't looked into this in detail, it appears Windows
clients always use the same ICMP ID--512...


>echo %os%
Windows_NT

>ping 199.185.137.3

Pinging 199.185.137.3 with 32 bytes of data:

Reply from 199.185.137.3: bytes=32 time=117ms TTL=242
Reply from 199.185.137.3: bytes=32 time=118ms TTL=242
Reply from 199.185.137.3: bytes=32 time=118ms TTL=242
Reply from 199.185.137.3: bytes=32 time=118ms TTL=242


# uname -a
OpenBSD openbsdvm.internal.melameth.com 3.7 GENERIC#50 i386

# ping -c 5 199.185.137.3
PING 199.185.137.3 (199.185.137.3): 56 data bytes
64 bytes from 199.185.137.3: icmp_seq=0 ttl=242 time=129.318 ms
64 bytes from 199.185.137.3: icmp_seq=1 ttl=242 time=128.110 ms
64 bytes from 199.185.137.3: icmp_seq=2 ttl=242 time=100.227 ms
64 bytes from 199.185.137.3: icmp_seq=3 ttl=242 time=159.927 ms
64 bytes from 199.185.137.3: icmp_seq=4 ttl=242 time=153.973 ms
--- 199.185.137.3 ping statistics ---
5 packets transmitted, 5 packets received, 0.0% packet loss
round-trip min/avg/max/std-dev = 100.227/134.311/159.927/21.297 ms


# uname -a
OpenBSD mel.internal.melameth.com 3.7 GENERIC#50 i386

# ping -c 5 199.185.137.3
PING 199.185.137.3 (199.185.137.3): 56 data bytes
64 bytes from 199.185.137.3: icmp_seq=0 ttl=242 time=117.295 ms
64 bytes from 199.185.137.3: icmp_seq=1 ttl=242 time=124.281 ms
64 bytes from 199.185.137.3: icmp_seq=2 ttl=242 time=115.875 ms
64 bytes from 199.185.137.3: icmp_seq=3 ttl=242 time=119.523 ms
64 bytes from 199.185.137.3: icmp_seq=4 ttl=242 time=123.472 ms
--- 199.185.137.3 ping statistics ---
5 packets transmitted, 5 packets received, 0.0% packet loss
round-trip min/avg/max/std-dev = 115.875/120.089/124.281/3.320 ms


...and the output from the gateway which reflects the machines above
respectively:

$ sudo pfctl -ss | grep icmp
self icmp 192.168.x.x:512 -> 207.224.x.x:512 -> 199.185.137.3:512
0:0
self icmp 192.168.x.x:51726 -> 207.224.x.x:51726 -> 199.185.137.3:51726
0:0
self icmp 192.168.x.x:5903 -> 207.224.x.x:5903 -> 199.185.137.3:5903
0:0