Command timeouts don't works. For example:

# dip -t
DIP: Dialup IP Protocol Driver version 3.3.7o-uri (8 Feb 96)
Written by Fred N. van Kempen, MicroWalt Corporation.

DIP> port modem
DIP> wait TEST 1

This command is not finished after 1 second, because SIGALRM
does not interrupt read() function by default. Solution is to
use siginterrupt:

--- dip-3.3.7o/main.c.alrm      Mon Nov 15 22:05:59
1999
+++ dip-3.3.7o/main.c           Mon Nov 15 22:06:08
1999
@@ -398,2 +398,3
@@
   (void) signal(SIGQUIT,
catch);
+  (void) siginterrupt(SIGALRM,
1);