> > sorry could you tell me what's the command. i have no experience using gdb
>
>  #gdb /path/to/program /path/to/core
>  gdb /usr/libexec/telnetd /telnetd.core
>  bt

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This GDB was configured as "i386--netbsd"...(no debugging symbols
found)...
Core was generated by `telnetd'.
Program terminated with signal 11, Segmentation fault.
Reading symbols from /usr/libexec/ld.elf_so...(no debugging symbols
found)...
done.
Reading symbols from /usr/lib/libutil.so.5...(no debugging symbols
found)...
done.
Reading symbols from /usr/lib/libtermcap.so.0...(no debugging symbols
found)...
done.
Reading symbols from /usr/lib/libtelnet.so.4...(no debugging symbols
found)...
done.
Reading symbols from /usr/lib/libkrb5.so.16...(no debugging symbols
found)...
done.
Reading symbols from /usr/lib/libkrb.so.5...(no debugging symbols
found)...
done.
Reading symbols from /usr/lib/libcrypto.so.1...(no debugging symbols
found)...
done.
Reading symbols from /usr/lib/libasn1.so.5...(no debugging symbols
found)...
done.
Reading symbols from /usr/lib/libcom_err.so.4...(no debugging symbols
found)...
done.
Reading symbols from /usr/lib/libroken.so.12...(no debugging symbols
found)...
done.
Reading symbols from /usr/lib/libc.so.12...(no debugging symbols
found)...done.
#0  0x804ab7d in telnet_spin ()
(gdb) bt
#0  0x804ab7d in telnet_spin ()
#1  0x804f242 in telnet_spin ()
#2  0x804db29 in telnet_spin ()
#3  0x804dff5 in telnet_spin ()
#4  0x804d9f5 in telnet_spin ()
#5  0x804a04e in encrypt_end ()