Hi guys, I have this problem with my Linux box, it's centos 4, this thing I'm using as some db server and web server, it's on public IP,
no firewall.
also no firewall on the os itself. somehow I cannot login to this machine from 1 IP, it's the Ip of my workplace. so from home, and from anywhere else I can login, to ssh, and http, no problem. but when I try to login form office IP it does not let me in, I cannot even ping my box from office. so it's very strange thing, this Linux I installed on collocation, it was directly connected to public dedicated internet connection and I set a static IP settings. So I'm just lost in this, I don't know where to start looking.
Please advise.

thanks.

If the box is visible from everywhere except work, I'd be asking the system admins at work if they're blocking the traffic. If not, have you tried using wireshark to sniff the traffic to see which side is not sending packets (you won't be able to read the content, just check connections) or looking through your logs for errors?

Hi, I made some trafcapture, and I can see only syn, no ack, I did about 1minute capture, with 3 requests 2 from my ie and fireox, and 1 with ssh, I can see only syn packets, nothing alse, no errors, no acks, nothing.

If that's the traffic capture results from your box at work it sounds like the packets aren't getting to your box at home. Since you have a running SSH at home, if the traffic was being rejected, you'd get a message back. Have you spoken to the system admins where you work to see if they block SSH traffic?

Also, are you saying that you can't use IE or Firefox to see your web server either? If that's the case and you know that your web server is working, I'd also check your ISP to see if they're blocking traffic.

Hi, well in our office I'm the admin, so I cheked my firewall but nothing is blocked, and also I'm using ssh to another remotes, so that's working 100%, but about the ISP, I think you are right, I called them, and sent them the sniffer log, and i cheked also simple with win: tracert. that shows only traffic till the isp gateway, so after my contact with them they promised to chek why is it stopped by the gate. I'm waiting for reply now, after their reply I will post the result here.
thanks sofar .

this is the greatest forum.

If it is your ISP and they can tell you what ports they do allow, I'd change the port that your SSH daemon is running on from 22 to whatever they provide. For example, since sshd_config supports multiple port entries you could have:
You can also use the Listen directive to specify the IP address as well as the port.

No, thats not the problem, our ISP's in Netherlands do not block anything, we don't have that kind of problems in NL, it's democracy :-). the problem is in the gateway, cause I can use ssh default port to another IP addresses, it's only giving me problems with this IP address. not with others. so in first place I was thinking that it's in the computer the problem, maybe some firewall, than I formated the disk and installed fresh Linux centos 4. after that I only set the static IP and checked if all firewall stuff is turned off. so after that I still wasn't able to login, than I made the trace after the suggestion of 'gilead' and saw that traffic never goes further than the gateway of my ISP, so that's the problem, cause in case of some block I can see that my machine blocks, and because I know that I do ssh to others, there is no block by ISP, there is just some problem with gateway.

Hi guys, my problem is solved, seems that my ISP's gateway was blocking the IP. sombody requested the IP to be blocked from our company, years before, so that was when we had some special server on that IP, now it's removed form black list. so I'm able to acces it.
thanks to gilead for advising, it was not so hard, I'm doing that kind of stuff not for the first time, but somehow I didnot do any trace when I got this problem, thanks for advise and help.

regards.

I'm glad you were able to solve the problem - congratulations