[Gllug] pinging through NAT very slow

[Martin A. Brooks]

I have a machine quite newly installed running a simple NAT. Generally, 
it works fine except for it's incredibly slow and gives some packet loss.




martin at martin-laptop:~$ ping www.google.com
PING www.l.google.com (216.239.59.104) 56(84) bytes of data.
64 bytes from 216.239.59.104: icmp_seq=1 ttl=245 time=20.7 ms
64 bytes from 216.239.59.104: icmp_seq=2 ttl=245 time=17.4 ms
64 bytes from 216.239.59.104: icmp_seq=3 ttl=245 time=19.3 ms
64 bytes from 216.239.59.104: icmp_seq=5 ttl=245 time=19.7 ms
64 bytes from 216.239.59.104: icmp_seq=6 ttl=245 time=77.9 ms
64 bytes from 216.239.59.104: icmp_seq=7 ttl=245 time=33.3 ms

--- www.l.google.com ping statistics ---
7 packets transmitted, 6 received, 14% packet loss, time 26265ms


Whereas from the server:

off0crm01:~# ping www.google.com
PING www.l.google.com (66.102.9.99) 56(84) bytes of data.
64 bytes from 66.102.9.99: icmp_seq=1 ttl=246 time=20.4 ms
64 bytes from 66.102.9.99: icmp_seq=2 ttl=246 time=17.1 ms
64 bytes from 66.102.9.99: icmp_seq=3 ttl=246 time=23.1 ms
64 bytes from 66.102.9.99: icmp_seq=4 ttl=246 time=22.7 ms
64 bytes from 66.102.9.99: icmp_seq=5 ttl=246 time=40.3 ms
64 bytes from 66.102.9.99: icmp_seq=6 ttl=246 time=27.9 ms

--- www.l.google.com ping statistics ---
6 packets transmitted, 6 received, 0% packet loss, time 5006ms
rtt min/avg/max/mdev = 17.145/25.294/40.349/7.473 ms


off0crm01:~# iptables -L -t nat
Chain PREROUTING (policy ACCEPT)
target     prot opt source               destination
DNAT       tcp  --  anywhere             anywhere            tcp dpt:www 
to:192.168.10.252:3128

Chain POSTROUTING (policy ACCEPT)
target     prot opt source               destination
MASQUERADE  0    --  anywhere             anywhere

Chain OUTPUT (policy ACCEPT)
target     prot opt source               destination


I've changed the switch, network cable and NIC, no effect.  Any ideas?

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