I have severe problem accessing yahoo.com and yahoo.co.in and www.gmail.com.
I have connected tp internet by an proxy server.So it seems that admin. have blocked all the ports and website.In what way i can know that they have really blocked that website.

I mean is there any command to lookup the server they have blocked or can u pls tell me the port number of yahoo or gmail so that i will scan those port's by nmap....


The below result i get when i look the sebsite from command line

#lynx http://www.gmail.com


400 Bad Request
Google
Error

Bad Request

Your client has issued a malformed or illegal request.




















Commands: Use arrow keys to move, '?' for help, 'q' to quit, '<-' to go back.
Arrow keys: Up and Down to move. Right to follow a link; Left to go back.
H)elp O)ptions P)rint G)o M)ain screen Q)uit /=search [delete]=history list

It appears from the message that qmail doesn't like how lynx is attempting to open the page. If it were being blocked at your end you'd likely just see some sort of timeout.

Anyway you can see if you're locating by name with hostname / dig:

dig www.qmail.com

This should show you something similar to:

; <<>> DiG 9.2.2 <<>> www.qmail.com
;; global options: printcmd
;; Got answer:
;; ->>HEADER<<- opcode: QUERY, status: NOERROR, id: 44135
;; flags: qr rd ra; QUERY: 1, ANSWER: 1, AUTHORITY: 3, ADDITIONAL: 0

;; QUESTION SECTION:
;www.qmail.com. IN A

;; ANSWER SECTION:
www.qmail.com. 60 IN A 208.186.64.119

;; AUTHORITY SECTION:
qmail.com. 60 IN NS post.forevermail.com.
qmail.com. 60 IN NS host1.forevermail.com.
qmail.com. 60 IN NS dns1.forevermail.com.

;; Query time: 236 msec
;; SERVER: 10.0.4.51#53(10.0.4.51)
;; WHEN: Thu Oct 20 08:24:34 2005
;; MSG SIZE rcvd: 117


The ANSWER SECTION lets you know it found an IP for qmail.

To test whether you're being blocked completely just try ping:

ping www.qmail.com

If it shows no packets lost then your not blocked from the site (though you still may be blocked on a port). You can try telnet to see if you can get to the port. Default port for web pages is 80:

telnet www.qmail.com 80

You should see something like:
Trying 208.186.64.119...
Connected to urls.forevermail.com (208.186.64.119).
Escape character is '^]'.

You then hit Ctrl and right bracket (]) to get the telnet prompt then type "close" to exit the session. The "Connected to..." in the above output lets you know the port is open.

Note that lynx is a text browser. Your issue may simply be it doesn't want you to use a text browser and you'll need to use a graphical browser like Firefox.

i know my problems.
i can not use host or dig or nslookup or telnet for www.xxx.com because every thing is blocked in my university.So the output will be...

[root@localhost /]# telnet www.qmail.com 80
www.qmail.com/80: Temporary failure in name resolution
[root@localhost /]# dig www.qmail.com

; <<>> DiG 9.2.3 <<>> www.qmail.com
;; global options: printcmd
;; connection timed out; no servers could be reached
[root@localhost /]#

Actually my question is how to see or get an info. either gmail is blocked by
querying the proxr server or whatever form?

"no servers could be reached" means "no name servers could be reached. That along with everything you just wrote don't indicate blocking to me. They indicated an issue with name resolution (DNS). Most likely in /etc/resolv.conf. We'll skip that for a moment.

To check blocking you could try the IP I gave you in my first response. If you type in IP it doesn't need to do name resolution. So try:

ping 208.186.64.119

If that is succesful try:

telnet 208.186.64.119 80

If that is successful then you're not blocked. Your issue is just name resolution.

In that case have a look at /etc/resolv.conf. This file specifies which nameservers you should be using. Just try pinging those and see if they're OK. If not or if you have no servers defined in /etc/resolv.conf you'll need to ask your Network admins the correct name servers to use.