mTCP works, but fails on most connections

[Plopilpy]

Hi Mike,

I just installed mTCP (as well as the Arachne browser) on my DOS VM the other day, and followed a guide on how to set everything up. However, mTCP has been giving me some trouble.

First off, most connections made don't work. I've tried using most of the terminal applications included with mTCP, and almost all of them fail to connect. The only applications that work successfully are DHCP and SNTP. The rest of them fail when any connections are attempted. I can confirm that my packet drivers are working, they give me a MAC address when run. As for DHCP, despite it being one of the few applications that successfully connect, it still causes a "bad request" error on every site I visit in Arachne. I also tested using DosLynx, just in case Arachne was broken, but DosLynx cannot connect to any site either, logging that BOOTP/DHCP failed.

Arachne can only connect to two sites: arachne.cz, and www.tim.org. Any other site, regardless of TLS or SSL versions, cannot be visited because of bad requests.

Any help would be greatly appreciated.

[Michael Brutman]

Hi,

Arachne is not part of mTCP and I don't use it, so let's concentrate on getting mTCP sorted first.  If DHCP and SNTP are working then you are able to send and receive UDP packets, so there should be no problems with TCP.

Questions:

• Have you tried ping and going to a few different sites? (brutman.com, google.com, etc.)
• HTGet should let you download a text page from a web site.  Try htget -o index.htm http://www.brutman.com/ and see if you get the HTML for my site.
• FTP should work but you need to find a public FTP server.  ftp.oldskool.org works well

If you can't ping or connect to any of these then you should check the following:

• DNS setting: Did DHCP get a bad DNS setting from the router?
• Virtual machine settings: Are you using Bridge mode (recommended), NAT (might work) or Host only (definitely will not work)?
• Host settings: If you are running on a VM then your packets are going through the host operating system.  Some host operating systems use TCP "offload" functions to let the network card handle IP checksums, and that may be causing problems on your system.
• Firewall settings

Lastly, I gave this list of things to look at because your problem description is too generic.  We can eliminate some of these if you share what host OS you have, what virtual machine you are using, the VM network settings, and a trace from one of the mTCP apps that is not working.  Tracing (and everything else) are covered in the PDF docs.

-Mike

[Joel Pérez]

Hi.

Regarding the "bad request" that Arachne gets, I think the problem may be due to the HTTP version that this program uses. In my case, the browser also gets that error for many other websites.

In order to determine what headers the Arachne browser sends, I have entered the following url:

http://www.xhaus.com/headers

And the page loads correctly, showing the HTTP Headers that the Arachne browser sends.

In the top section, the page shows the column "Request parameter", which for "Protocol Version" has the value "HTTP/1.0".

Subsequently, I exited Arachne, and then opened the "Dillo" browser, and with it I was able to successfully open many web sites.

Checking the HTTP Headers sent by this browser, I saw that the Protocol Version it sends is HTTP/1.1.

I hope it has been useful for you.

Best regards!

[Michael Brutman]

HTTP/1.0 is definitely going to be a problem on the modern web as much of it is on shared web hosts.  HTTP/1.1 adds the "Host" request header option which is needed for shared web hosts.

[Plopilpy]

Huh. This is weird. I typed out a full response but I sent it and it's not here. It might've sent privately. Mike, if you could see if you received it then that'd be nice.

[Michael Brutman]

(I received it directly as an email ...  next time you have to reply to all.)

Summarizing the email:

• Ping, htget, and ftp worked.
• ftp: If you want to cancel out of the username or password prompt you can hit ctrl-c or ctrl-break.
• You are using bridge mode in the VM with the PCNet-Fast III emulated device
• Visit various sites fails: I assume you are still talking about Arachne here?

So it sounds to me like all of the mTCP programs are working fine, and this is not an mTCP problem.  Arachne does not use any part of mTCP so it has its own DHCP and TCP/IP code.  You should check to see if the network settings it is using are correct.  You also might be using an out-of-date version of it; you should check that and update to the latest version.  (FreeDOS 1.3 has Arachne included; you should see what they are using.)

-Mike

[Plopilpy]

I'll duplicate my install and remove mTCP on the copied version, just to confirm if you're correct.

[Plopilpy]

Okay, I've confirmed that Arachne does indeed have its' own DHCP built in.

And, about the version: I was using the latest version, but it turns out I was using too new of a version. I had Arachne 1.99 installed, but it turns out that Arachne 1.95 was the version I needed.

It's working great now, thank you so much for the help Mike!