telnetd: All network ports in use. What do I do ?

[Ole Nomann Thomsen]

Does anyone know what to do about the "telnetd: All network ports in use."-
error message, when connecting to a unix-system via telnet ? Sometimes
my ATT-unix puts itself into a state, where it will only accept one in-
going telnet. Trying to open more results in this error.

I looked in the telnetd.c source, and it seems that this error comes when
the telnetd is unable to open any /dev/ptyp?? pseudo-terminal-masters,
so it seems to be a problem with the pty-drivers.

I have a snip of code, that tries to open the /dev/ptyp??'s, and calls
perror if it fails. When I tried this, I got "I/O error" on all of them
with the system in the above state. (normally they can be opened,
okay, but only once. My opening them seems to foul things up too).

I tried 
        chown(<pty>, 0, 0); chmod(<pty>, 0666);
        chown(<tty>, 0, 0); chmod(<tty>, 0666);

As in the telnetd.c, to no avail. The pty's stay unavailable.

My questions are:

1. Why does the pty's suddently become unopenable ?
2. What can I do to remedy the problem (*Besides* rebooting, please)

Hope someone takes pity and helps me

-- 

- Ole. (nomann at diku.dk).