Problem with bind system call over slip link

[Rob Liebschutz]

I'm running a slip connection between a sun 3/80 running SunOS 4.0.3 and a
Cisco terminal server.  The slip connection gets established, and telnet
sessions work fine.  The problem that I'm having is that programs such as
ftp that use the BIND system call don't work.  Bind fails with error 49
EADDRNOTAVAIL (Can't assign requested address) (on the Sun 3/80 end).
I've used the debugger and found that bind is trying to bind the ip
address of the slip interface to the socket which it has created for ftp's
data connection.  Yes, ftp does an SO_REUSEADDR ioctl on the socket before
calling bind.

I've already looked for the possibility of a problem in the reverse
mapping of IP address to hostname and can't find any.  A call to
gethostbyaddr returns the fully qualified hostname of my machine which is
identical to the string set by the hostname command.

If I shutdown slip and ifconfig le0 to the same ip address, I am able to
ftp to my own hostname (and I couldn't when slip was running).

It would seem that the solution to this problem should be very
straightfoward.  Any ideas?  If not, it would be useful to know under what
conditions the bind system call returns the EADDRNOTAVAIL error.

The only thing odd about my configuration is that the slip software on the
Sun seems to want to use point to point links for the connection, but the
Cisco terminal server running 7.?? doesn't.  I've told the slip software
on my Sun that the IP address at the other end of the point to point link
is the IP address of the terminal server.  This seems to work fine, at
least for passing IP packets.

Thanks,
Rob