Ehlo Problem

[thsuniki]

Hallo,

we have a Proxmox 2.2 Mailgateway and use it for in- and outgoing mails.
Now we have a problem to send mails to one customer.
"timed out while performing the EHLO"
Today we get a instruction from customer to test the problem.

Ответ на EHLO:

telnet 77.91.130.192 25
Trying 77.91.130.192...
Connected to mail.comstyle.com.ua.
Escape character is '^]'.
220 mail.comstyle.com.ua ESMTP Sendmail 8.13.1/8.13.1; Mon, 8 Sep 2008 13:59:00 +0300 (EEST)
ehlo ip.ukrtel.net
250-mail.comstyle.com.ua Hello 104-127-207-82.ip.ukrtel.net [82.207.127.104], pleased to meet you
250-ENHANCEDSTATUSCODES
250-PIPELINING
250-8BITMIME
250-SIZE
250-DSN
250-ETRN
250-DELIVERBY
250 HELP

Ответ на HELO:

telnet 77.91.130.192 25
Trying 77.91.130.192...
Connected to mail.comstyle.com.ua.
Escape character is '^]'.
220 mail.comstyle.com.ua ESMTP Sendmail 8.13.1/8.13.1; Mon, 8 Sep 2008 14:01:40 +0300 (EEST)
helo ip.ukrtel.net
250 mail.comstyle.com.ua Hello 104-127-207-82.ip.ukrtel.net [82.207.127.104], pleased to meet you


I try it from my pc, it works. I login as root on Proxmox and i get a timeout while ehlo.
Where is the problem?

Thanks,
Thomas Fuhrmann

 

[dietmar]

Most likely a firewall problem. We ovserved such behaviour with old zywall firewalls (bios updates resolved the problem).

- Dietmar

 

[thsuniki]

It can't be a firewall problem. We have the Problem since july. In july we change our exchange5.5 to david10. With exchange we couldn't use proxmox for outgoing mails and the problem does not exist.
David should use proxmox. 14 days ago we also change our firewall to a new system.

Thanks

 

[dietmar]

The problem can also be a firewall/gateway somewhere on the route to that host. Did you talked to that customemer, asking him what firewall he has. What firewall product do you use?

- Dietmar

 

[thsuniki]

Now we have a Lancom 8011 Firewall.
The customer get e-mails from all other, but not from us.

Thomas

 

[dietmar]

And what kind of firewall has the customer?

 

[thsuniki]

I don't know.
But if I try the telnet from a client in the same subnet like the proxmox and behind the same firewall, it works ok.
If I try telnet on console from proxmox, it don't work.

Thomas

 

[dietmar]

The problem you describe looks like a TCP/IP MTU resizing bug. I can just tell you that this is most likely a problem with the firewalls involved.

- Dietmar