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Some strange access problem between 2 SME's

Offline allun

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Some strange access problem between 2 SME's
« on: January 09, 2005, 04:53:00 AM »
Ok, I'll try and explain this clearly....bcos it's buzzing round in my head and not making any sense at the moment (too much staring at the screen and too much caffeine....)
 
I have several SME 6.0 servers around the country that I manage.  Between 2 of them there is some sort of weirdness going on - they can't talk to each other.

Both are SME 6.0, with the same contribs, and set up the same (as server/gateways on ADSL with the same ISP).

The problem is that one server can't see the other - they can't connect via http, ssh, smtp....anything!

Pings and traceroutes both fail.

However, both servers are accessible just fine from (seemingly) anywhere else on the net - it's just between the two of them that there is a problem!
 
I only noticed this after a reboot of one of the servers, so i think it's a problem with that particular one, the last things installed on that server were Xoops then ClamAV.

I'm thinking it's gotta be xinetd or some other access control system, but could that affect traffic in both directions between the 2 servers??? And how could that stop basic IP tests like a ping?

Aaargh.  Even just writing this out makes me think - there can't be any way that a server config is stopping the ADSL routers from replying to pings....that's one area where I'm fuzzy - I have configured the routers at both ends to pass ALL traffic through to the server.... so I wonder if that means ICMP packets are being passed thru to the server as well?

Anyway....hoping someone can suggest where to look or what to try :-)
...

k_graham

Re: Some strange access problem between 2 SME's
« Reply #1 on: January 09, 2005, 05:50:13 PM »
Quote from: "allun"

I have several SME 6.0 servers around the country that I manage.  Between 2 of them there is some sort of weirdness going on - they can't talk to each other.

Both are SME 6.0, with the same contribs, and set up the same (as server/gateways on ADSL with the same ISP).

Anyway....hoping someone can suggest where to look or what to try :-)


"The same ISP" - is a likely culprit. I had the problem that 2 could not communicate with each other when the 2 units were within the same IP range ( all but last 3 IP numbers the same on the outgoing IP, in the case of a fixed ip) My ISP confirmed they had the same problem to contend with. This has further repercussions in that you can talk to the entire world but not your 254 neighbours which might be customers.

In the above case my ISP re-assigned me an IP in a range they use with a bunch of modem hookups, so I wouldn't have a problem with other local clients trying to get to my site. They stated it doesn't happen with modem hookups but only with 2 fixed IP systems.

The possible reason for the above problem stated was that it may be to prevent unmeasurable band width between 2 systems and a implementation of the telco that provided the switching system.

Another possibility if I recall is that you are using the same local IP range at each location, if so break them up (192.168.x.x; 10.x.x.x or 172.16.x.x).
I did a quick google search on this problem and came up with
http://www.tek-tips.com/threadminder.cfm?pid=1355
http://www.learntosubnet.com/
Guess I also have some reading to do.

Ken

 

Ken