Topic: Server not accessable, but from ONLY ONE IP address.

[TeX]

Good evening all-

As a newcomer to the Linux world, I’ve installed and setup SME 6.0.  All has been running great for over a year now, and now suddenly I’ve got an issue.  Not necessarily wanting to rebuild the server, was wondering if anyone has some advice.  My domain hosts both a website and email.  Again, everything has worked for well over a year now, but I cannot access my webpage, nor can I send email to my domain, but ONLY from my office.  I have tested web services/email from a few different dial in ISPs and it works great, so I know it’s not DNS related.  I have also done a NSLOOKUP from the office, so I know it’s not our DNS.  The only firewall is the server itself.  I have contacted my ISP, and they do NOT filter content or block anything.  I have checked with my network engineers and messaging team, and they are not blocking/filter anything with my destination address from the office side.  Is there a configuration setting in SME that could have suddenly begin to block or blacklist a single IPs?  Any help or advice would be greatly appreciated.

Regards,
Mike

[cc_skavenger]

It might be dns related, on the server itself.  Have you changed your ISP provider or did they change providers?  Sounds like the server has incorrect entries in the server manager for your www and mail settings.  Log into the server manager and click on the hosts and addresses panel and check the ip information listed there for your domain.

HTH

[TeX]

Well, here I go again.  After spending a lot of time researching the problem above, I decided to rebuild the server since that is a fairly quick process.  Everything was back to normal working great (basically for almost two months).  Last night, I bounced the server, and now I'm back to square one.  I can access my site/email from anyplace on the internet with one exception.  The only thing I can think of is when I bounced the server, I was also connected via VPN to my office network.  Is there someplace I am failing to look that may have somehow added this network address to an ACL?  I have bounced the server several times, since, but no access from the office.

Again, extract same issue as stated above.  Everything working fine for weeks and months, but after a reboot of the server I can no longer access my site, but only from ONE network.  Any thoughts?

[wyron]

If you are running an 'intelligent' Cisco-firewall at the office, that might be the cause, especially if your isp doesn't provide reverse DNS.
It is for me, seeing that my private ip has been blocked automatically by the damned firewall!
I can access my router at home (answering on 8080), but not my network.
Not even a VPN-connection attempt can get the answer from the router back through into the office network.
Perhaps a word, whispered into the ears of the wizz-kids managing the firewall at your office will help you more than it did me.

[TeX]

Thanks for the advice however since I had been down this road before, and know that rebuilding the server solves the problem, proves it’s not DNS related or office network related.

I know now for second time, with proof the fact is that it’s something related to the server.  I took a spare machine last night and yet again reinstalled the 6.0.1 server, and guess what, things work perfectly from the office today!  

I then moved the network cable back to the original server and nothing, but again, only from the office.  Tested using 3 other ISP providers and it works great.  

Somehow and somewhere in the configuration of my existing server access from a particular domain/IP is being restricted/denied.  For now, I’m not interested in rebuilding the actual server since it requires time and effort to save emails and files (and I’m the only one at the IP being blocked), so if anyone has some thoughts on items to check within the server itself, it would be greatly appreciated.

[kruhm]

you are going to have to look through the logs to find out what the error is and post them.

did you restore from a backup on the 2nd build? or was it a brand new install? if it was from backup, it maybe an incorrect setting in a config somewhere.

put a hub inbetween your server and your firewall (this is a server-only install, right?). Then hook up a pc to see if you can access it from there. if so, then it's a firewall issue. if you're using a low/mid-end firewall/router, it may have to be rebooted/replaced/rebuilt.

if it's a server-only install, make sure you have the dns server's configured in initial setup. while there is a fully-enabled dns server inside sme, in my experience it doesn't work correctly if it's in server-only mode.