fastforward problem

Brian Candler B.Candler at pobox.com
Sun Feb 12 04:51:34 PST 2006


On Sat, Feb 11, 2006 at 05:35:33PM +0100, GiZmen wrote:
> I would like to use fastforward option on my freebsd 6.0-stable
> box. But i have strange problem with it. My box is a router for LAN
> with IP visible to internet. I am managinc C class network.
> When i turn on fastforward option any of the computers in my network
> can't open google.com page. This option is quite good because i have
> quite a lot interrupts and this option lower this about half.
> Could anyone tell me why i can't open google.com page ?
> I have tested different pages and i don't have such problem only with
> google.

Just saying "I can't see google.com" is not a good diagnosis of the problem.
If it's your job to manage a router, then you need to be able to do lower-
level tests to isolate the problem.

Check each of the components in turn:

(1) can my client resolve google.com in the DNS?

If the client is some sort of Unix then try

$ nslookup google.com

You should see a response such as:

Non-authoritative answer:
Name:   google.com
Address: 72.14.207.99
Name:   google.com
Address: 64.233.187.99
Name:   google.com
Address: 64.233.167.99

(2) can my client ping these addresses? That is, is there layer 3 network
reachability between my network and theirs?

$ ping 72.14.207.99
PING 72.14.207.99 (72.14.207.99): 56 data bytes
64 bytes from 72.14.207.99: icmp_seq=1 ttl=238 time=133.730 ms
64 bytes from 72.14.207.99: icmp_seq=2 ttl=237 time=133.179 ms
64 bytes from 72.14.207.99: icmp_seq=3 ttl=238 time=133.316 ms
64 bytes from 72.14.207.99: icmp_seq=4 ttl=237 time=133.396 ms
^C
--- 72.14.207.99 ping statistics ---
5 packets transmitted, 4 packets received, 20% packet loss
round-trip min/avg/max/stddev = 133.179/133.405/133.730/0.203 ms

(3) what happens when I open a TCP/IP connection to port 80, and manually
fetch a HTTP page?

$ telnet 72.14.207.99 80
Trying 72.14.207.99...
Connected to 72.14.207.99.
Escape character is '^]'.
GET / HTTP/1.0
Host: google.com
                                         <<<<< end with a blank line
HTTP/1.0 301 Moved Permanently
Location: http://www.google.com/
Set-Cookie: PREF=ID=f811e9355f349c08:TM=1139748428:LM=1139748428:S=UhZOEU98p2mnw_H0; expires=Sun, 17-Jan-2038 19:14:07 GMT; path=/; domain=.google.com
Content-Type: text/html
Server: GWS/2.1
Content-Length: 219
Date: Sun, 12 Feb 2006 12:47:08 GMT
Connection: Keep-Alive

<HTML><HEAD><meta http-equiv="content-type" content="text/html;charset=utf-8">
<TITLE>301 Moved</TITLE></HEAD><BODY>
<H1>301 Moved</H1>
The document has moved
<A HREF="http://www.google.com/">here</A>.
</BODY></HTML>
Connection closed by foreign host.

OK, that's fine. google.com has redirected me to www.google.com. So try the
whole process again with www.google.com instead of google.com

Brian.


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