It seems like whatever the version of zlib is, the message "zlib too old" which precedes the installation failure always appears if the option --without-zlib-version-check is not used while calling the configure script. Reminder : Openssh needs at least zlib version 1.2.3. If someone checks the configure script then check the line 10672 : one can see that the script checks if the variable $zlib_check_nonfatal is set : [line10672] if test -z "$zlib_check_nonfatal" ; then - If the variable $zlib_check_nonfatal is set then "zlib too old" does not happen. The big problem is that the only other place where $zlib_check_nonfatal could be set is at line 10598 : [line 10598] zlib_check_nonfatal=1 which ONLY happens if --without-zlib-version-check is used. May be my mistake... so if someone could check that and have a correct zlib version check that would be nice. Best regards.
Your analysis is incorrect - the test for $zlib_check_nonfatal checks whether it is blank or not. An unset shell variable is equivalent to a blank one, so this is fine. I'm not sure I understand what your problem is: are you saying that configure misdetects your zlib as too old? If so you will need to provide more information, such as the version of zlib you have installed and the generated config.log.
Ok, I try to explain the problem. The point is that the configure script misdetects my non-local zlib version. I have zlib version 1.2.3 installed /usr/lib /lib /usr/include and I have zlib version 1.2.1 in /usr/local/lib /usr/local/include Sorry for reporting it as a bug but the version detected by the configure script is version 1.2.1. I have just taken off /usr/local/include/zlib.h and the configure script works perfectly. Is that normal that the configure script checks a local version in /usr/local/include/zlib.h against the root system-wide version in /usr/include/zlib.h ? It must be my mistake with my environment definition. I am sorry I haven't seen the full "if" condition line 10696 of the configure script which certainly needs some smarter indentation.
Close bugs fixed/reviewed for openssh-5.2 release