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Hi After hours of searching and lots of calls with the ISP someone from the ISP gave me the hint. It is not a m0n0wall problem, it is a problem with a router which does not properly handle MTU/MSS. The router is between the customers home network and his office... its a Draytek Vigor!! So dont use this routers!!! thanks a lot for all the help regards Andreas Andreas Ferrari schrieb: > Morning > > Ok i missunderstod you and yestarday was not really my day. > I hope you accept my excuse. > Yes the postfix server works, I tested it with other VPN connections and > large Mails so it cannot be the a problem of the postfix server. > I also checked the transfer of files to the fileserver. > Maybe its really a problem with the Memory of the M0n0 or the FlashCard, > hope it works with a new one. And the last option is the MTU story.. > I will keep you up-to-date.... > > Neil A. Hillard schrieb: > >> Jeff, >> >> In message <4523CF99 dot 1050406 at buehlertech dot com>, Jeff Buehler >> <jeff at buehlertech dot com> writes >> >>> I think Neil is just saying it may be worth exploring other possible >>> reasons for the email to be failing rather than focusing on the bad TCP >>> checksums, which may or may not be related (is that right, Neil?). It >>> seems to me that that woulds be a indication of part of the problem, >>> though, but it may confuse the issue. For example, are you certain >>> that the Postfix server doesn't have problems with large emails in >>> general? I was having an issue with a mail server that had memory >>> corruption due to memory timings in the bios that ONLY failed on very >>> large email transfers (over 1.5 meg) and it took me quite a while to >>> discover the cause, or even the problem, since none of my users >>> reported it for a very long time. >>> >>> If it were me, I would try sending large emails from other locations to >>> verify the server is functioning properly (just to discount that as a >>> possibility), then I would try sending large files from the M0n0 VPN >>> via FTP to see if the failure is specific to SMTP. I would suspect >>> memory on the M0n0, or the network card. I have found with M0n0wall >>> that using IPSEC changing the type of compression makes a difference >>> with MTU issues (PPTP doesn't have that option). Finally messing with >>> MTU settings is the only thing left, and I have had very significant >>> problems that were hard to correct with MTU (just changing this and >>> that didn't work - it required very deliberate changes on a number of >>> systems along with reboots in some cases) running M0n0wall to Windows >>> systems specifically. >> >> >> >> Yep. My point was that the bad checksums may just lead you down the >> wrong path and waste your time. >> >> To confirm whether this is a problem or is just TCP offloading, perform >> a packet capture using a separate machine, either in a tap, a spanned >> port on a manageable switch or a hub. >> >> At least that way you'll know if this really is a problem. >> >> HTH, >> >> >> Neil. >> >> >>> Andreas Ferrari wrote: >>> >>>>> This is probably a red herring. >>>> >>>> >>>> Thanks for your answer.... >>>> >>>> Dou you think i will report something that i have dreamd? >>>> >>>> The fact is that it still not working, I tried lowering the mtu >>>> without sucess... >>>> So if you or someone have any ideas what there could be wrong please >>>> give me a hint. >>>> >>>> Neil A. Hillard schrieb: >>>> >>>>> Hi, >>>>> >>>>> I've been away for a while and haven't seen a response to this >>>>> but apologies if I've missed it. >>>>> >>>>> In message <451A397A dot 8010006 at stasoft dot ch>, Andreas Ferrari >>>>> <aferrari at stasoft dot ch> writes >>>>> >>>>> >>>>>> One of our customer has a VPN from his home office (wrap+m0n0 ver >>>>>> 1.22) >>>>>> to his office (wrap+m0n0 ver 1.22), that works fine. When he tries to >>>>>> send a mail from home over the VPN to the postfix server then the >>>>>> mail >>>>>> is never delivered to the mailserver. >>>>>> I noticed that small plaintext messages can be delivered to the >>>>>> postfix >>>>>> server but if the mail gets bigger then only the first part of the >>>>>> data >>>>>> are sent. >>>>>> On the mailserver i started tcpdump and could see that the mail could >>>>>> not be sent because there are a lot of bad tcp cksum messages. >>>>>> So the mailserver gets the first part right and the rest of the data >>>>>> are bad. How could that happend? >>>>> >>>>> >>>>> >>>>> This is probably a red herring. I suspect that you'll find that >>>>> this is >>>>> due to TCP Checksum Offloading. I spent a couple of days chasing >>>>> what I >>>>> thought were problems cause by this - turns out it was something else. >>>>> >>>>> HTH, >>>>> >>>>> >>>>> Neil. >>>>> >>>> >>>> >>> >>> --------------------------------------------------------------------- >>> To unsubscribe, e-mail: m0n0wall dash unsubscribe at lists dot m0n0 dot ch >>> For additional commands, e-mail: m0n0wall dash help at lists dot m0n0 dot ch >>> >> >> > > -- STASOFT AG P: +41 61 726 80 70 F: +41 61 726 80 79 |