telnetd: can't create pty?

Denys Vlasenko vda.linux at googlemail.com
Tue Feb 26 14:10:29 UTC 2008


On Tuesday 26 February 2008 14:45, Dirk Behme wrote:
> 
> Using BusyBox v1.9.1 on ARM target I want to telnet from PC to target. 
> Starting BusyBox telnetd on target as daemon and then connecting from 
> PC I get
> 
>  > telnet 192.0.0.2
> Trying 192.0.0.2...
> Connected to 192.0.0.2.
> Escape character is '^]'.
> Connection closed by foreign host.
> 
> on PC. Starting telnetd on target with -F I get
> 
> # telnetd -F
> telnetd: can't create pty
> 
> on target while PC tries to connect.
> 
> Any hint what's wrong here?
> 
> I used similiar configuration with some older BusyBox working quite 
> well. Now I switched to recent BusyBox and did some kernel 
> re-configuration.
> 
> Most probably this is a FAQ, and most probably I missed anything while 
> playing with configuration, but sorry, I can't see the obvious at the 
> moment. Searched already BusyBox ML archive, but couldn't find 
> anything similiar.
> 
> Many thanks
> 
> Dirk
> 
> Btw: I have
> 
> # ll /dev/pty
> /dev/ptyp0  /dev/ptyp6  /dev/ptypc  /dev/ptyq2  /dev/ptyq8  /dev/ptyqe
> /dev/ptyp1  /dev/ptyp7  /dev/ptypd  /dev/ptyq3  /dev/ptyq9  /dev/ptyqf
> /dev/ptyp2  /dev/ptyp8  /dev/ptype  /dev/ptyq4  /dev/ptyqa
> /dev/ptyp3  /dev/ptyp9  /dev/ptypf  /dev/ptyq5  /dev/ptyqb
> /dev/ptyp4  /dev/ptypa  /dev/ptyq0  /dev/ptyq6  /dev/ptyqc
> /dev/ptyp5  /dev/ptypb  /dev/ptyq1  /dev/ptyq7  /dev/ptyqd
> #
> 
> on my target and kernel is configured with
> 
> CONFIG_UNIX98_PTYS=y
> CONFIG_LEGACY_PTYS=y
> CONFIG_LEGACY_PTY_COUNT=256

Your busybox is probably configured with FEATURE_DEVPTS=y.
It requires POSIX pseudoterminals, not BSD. Do you have
/dev/ptmx? Do you have /dev/pts mounted?

# mount | grep devpts
none on /dev/pts type devpts (rw)

Fix this, or turn off FEATURE_DEVPTS for busybox.
--
vda



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