[Lilux-help] e-mail problems using Coditel-cable ISP

Fri May 28 12:45:35 CEST 2004

> i'm using coditel as well, and "I" can confirm that everything works as 
> usual!!!

Yes but you are on their static network:
Received: from simon.lan (cable-212.76.255.43.static.coditel.net
[212.76.255.43] .... 

I used to have an IP on that same network (although I never requested !)
until last weekend and never had any problem.
My ip changed on sunday night and since then I could connect to any
machines on port 25 ....

> i don't use the coditel mail service, i use other smtp servers.
> and those work and have never stoped from working.
> 
> you seem to have some other problem, OR coditel is blocking that port on you 
> both?
> but i don't see why they should do that....
> 
> On Friday 28 May 2004 07:53, Patrick LEMMERS wrote:
> > Hi,
> > I can confirm, for the last few days Coditel has been blocking outgoing
> > connection to port 25 to ANY machine !!!
> > Since this morning they are at least allowing connections to their
> > official  smtp relay (smtp.coditel.net) ...... Well done guys !!!
> >
> > It looks like they are trying to force their users to use only their
> > mail server for outgoing mail .... :-(
> >
> > a+
> > Patrick.
> >
> > On Thu, 2004-05-27 at 16:50, Eric Dondelinger wrote:
> > > Hi Serge,
> > >
> > > > For the past 4 weeks there have been increasing problems, first my
> > > > mails seemed to be rejected by Sendar for some obscure "IP forwarding"
> > > > question and Thierry helped me with that.  I had to fix my parameters
> > > > in Ximian Evolution and Kmail (I'm using both, yes, different e-mail
> > > > adresses, different "identities", different repositories etc...)
> > >
> > > ?? Sounds strange. -v please (maybe at the meeting tonight)
> > >
> > > > The last time I was able to send myil from my normal account was on
> > > > Sunday night, since then all I get is some error message saying "unable
> > > > to connect to sendar port 25".
> > >
> > > Try this:
> > > (as root), run tcpdump
> > > (as anyone), telnet sendar.prophecy.lu 25
> > > Check the tcpdump - you'll see the outgoing packets from your machine
> > > to sendar, you should also see the replies coming. If nothing comes
> > > back (not even ACKs), chances are your traffic is being dropped on
> > > the way - question is where.
> > >
> > > Oh yes, if the telnet works, you'll see this:
> > > bash-2.05b$ telnet sendar.prophecy.lu 25
> > > Trying 213.166.63.242...
> > > Connected to sendar.prophecy.lu.
> > > Escape character is '^]'.
> > > 220-sendar.prophecy.lu ESMTP Sendmail 8.12.10 ready at Thu, 27 May 2004
> > > 16:50:02 +0200
> > > 220 No Spam please!
> > >
> > > (close via "quit")
> > >
> > >
> > > Also try this (as root):
> > > nmap -p 25 sendar.prophecy.lu
> > > You should get:
> > > root # nmap -p 25 sendar.prophecy.lu
> > >
> > > Starting nmap 3.50 ( http://www.insecure.org/nmap/ ) at 2004-05-27 16:32
> > > CEST Interesting ports on sendar.prophecy.lu (213.166.63.242):
> > > PORT   STATE SERVICE
> > > 25/tcp open  smtp
> > >
> > > If it says filtered instead of open, again, we'll know packets are
> > > being dropped on the way. If it says closed, the packets are not
> > > dropped but rejected.
> > >
> > > > I _am_ able to retrieve my mails from Sendar though and I do receive
> > > > e-mails on each of my e-mail adresses.
> > >
> > > Different port...
> > >
> > > > I called Thierry and we checked a few things and it doesn't seem to
> > > > come from Sendar, so I called the Coditel (un)help-line to inquire.  As
> > > > usual they at first considered I might have problems with Outlook or
> > > > perhaps a trojan on my system, I explained that neither Kmail, nor
> > > > Evolution, nor Linux are all that suscpetible to windows virii (they
> > > > were actually understanding about that) and said there have been
> > > > "several" reports of users having trouble sending e-mail, they were
> > > > surprised though that I _am_ able to send e-mail with my Coditel
> > > > account (surprise, this works)
> > >
> > > ... which I assume you're sending via the Coditel mailserver?
> > >
> > > Note: whatever mail you're sending out, you're _always_ supposed
> > > to go through your ISP's mailserver. If you're trying to deliver
> > > mail directly, chances are that the recipient's mailserver will
> > > see your IP as belonging to a DUL (dial-up list), and thus refuse
> > > to talk to you (as much spam comes from dialups, be that analog,
> > > ISDN, dsl or cable).
> > > A From: (or envelope Mail From:) is easily forged, so if the
> > > server allows you to send mail based on that only, it's to be
> > > considered an open relay. If it uses pop-before-smtp or smtp-auth,
> > > things look better.
> > >
> > > Now, when trying the above - get Thierry to have a tcpdump
> > > running on his firewall (I bet there must be one ;-)) to see
> > > whether the packet arrives there. Give him your IP address
> > > first, so he can filter directly for your traffic. A short
> > > phone call will make sure it's no problem on TC's end.
> > >
> > > > 3) Sendar responds to ping, but I can't ssh to Sendar either, might be
> > > > similar filtering from Coditel, how can I investigate this?
> > >
> > > IMHO that would fit the bill.
> > >
> > > > 4) any other suggestions
> > >
> > > Ask Coditel whether they are filtering traffic. Ask them whether
> > > they block outbound SMTP traffic (unless going through their
> > > mailserver - this makes a lot of sense, considering all the mail
> > > resp. Outlook viruses as well as spam), ask them whether they
> > > filter anything else, whether they force your HTTP traffic
> > > through a proxy etc.
> > >
> > > I can very much symphathize with them if they are filtering
> > > outbound SMTP traffic (I'm seriously considering this measure
> > > @work), I can understand if they use a web proxy, I very much
> > > understand if they drop ports 137-139 traffic (SMB), but they
> > > certainly should bloody leave alone an SSH port (22).
> > >
> > > Note, I can symphatize/understand this, but if they do it, they
> > > should inform their customers, and offer their clued customers (tm)
> > > [not that there are many] a way around this. Personally, I wouldn't
> > > accept such a castrated internet connection (and lord, do I sometimes
> > > hate the one at work, where I'm in charge of the filtering myself ;-)).
> > >
> > > Greetings, Eric
> > >
> > > _______________________________________________
> > > Lilux-help mailing list
> > > Lilux-help at lilux.lu
> > > http://lilux.lu/mailman/listinfo/lilux-help
> 
> -- 
> 
> regards,
> Georges Toth
> _______________________________________________
> Lilux-help mailing list
> Lilux-help at lilux.lu
> http://lilux.lu/mailman/listinfo/lilux-help
> 
-- 
Patrick LEMMERS
patrick at lemmers.be 
http://patrick.lemmers.be 
Linux is like an indian tent: No Gates, no windows and an apache inside.