I've got a new CENTOS 5 (LINUX 2.6.18-53) server running with xinetd and the kerberos version of telnet (/usr/kerberos/sbin/telnetd), but I can't login using ZTERM. I can login fine if I start a telnet client from another LINUX box, and from a WINDOWS XP telnet client on the same box that I'm using for ZTERM.

What happens it that once I click connect, the yellow horizontal bar at the top of the screen lights up, indicating a connection has begun, but nothing happens after that.

I've done tcpdumps and I can see an exchange of packets, but the are many fewer packets exchanged on the zterm connection, which is logical as it never offers up a welcome message or login prompt.

The connection stays up for at least 27 minutes, but when ZTERM is closed I get this message in the system log from telnetd: "ttloop: peer died: Invalid or incomplete multibyte or wide character" I've seen one description that this error can be caused by the telnet client feeding the telnet daemon characters too fast, but that doesn't seem like a good fit here.

Has anybody else experienced this problem, and if so, have any solutions.

I had plenty of problems telnetting to a RHEL 5 system (basically the same as CentOS 5) that I set up for a customer a few months ago, but there I was getting some kind of cryptic error message immediately. I eventually worked around the problem by uninstalling the telnet package and installing an older one (telnet-server-0.17.31.EL4.3).

Aside from the above (which may have no relevance to your case), my suggestion would be to try to determine whether the issue is specific to telnet or applies to other telnet/ssh clients, such as the microsoft telnet, or putty, or even ATE. I'm not sure where we would go from there, but it might give some weight to the theory of it being some kind of quirk related to the client side.

I'll email you coordinates to see if you can connect to the RHEL5 system, which might cast light on whether the server side is the culprit.

Given that ZTERM is known to work with a ton of different telnet servers, clearly the problem stems with the telnet server I'm using on the CENTOS 5 system. But there must be some difference between ZTERM and other telnet clients that causes ZTERM not to work and other telnet clients to work.

Thanks for the offer of the test, but I can connect just fine with ZTERM with an SSH connection, and ATE works both in pure telnet mode and inside an SSH tunnel.

I suppose the answer is to try and find another telnet server. And perhaps I can get customers to start using ssh. (I do restrict both telnet and ssh access to specific or limited IPs.)

I found a generic non-kerberos telnet server (telnet-server-0.17-39.el5) on one of the CENTOS 5 mirrors, installed it, and all is well. I assume there is some subtly in the authentication process that ZTERM is not compatible with. Perhaps one more reason to be moving to ATE from ZTERM.

Well it seems that we both ended up with more or less the same solution (use an older telnet-server package). Let me warn you about one thing - it's easy to forget this in 6 months when installing updated packages. Depending on which update utilities you are running, you may want to see if you can add the telnet-server package to the list of packages to never update.