Resumed a old Win2000 VM with a correctly installed VC6 where lib and
include environment are correctly defined.
There is a FB 1.5.1 installed at the moment, I can change this with no
problem if mandatory to correct the error I'm reporting here.

I've enabled interbase shared option, the remaining options are the default.

nmake end reporting:
**************************** BEGIN ***************
ibase_blobs.c
main\streams/php_stream_transport.h(85) : error C2143: syntax error :
missing ')' before '*'
main\streams/php_stream_transport.h(85) : error C2081: 'socklen_t' :
name in formal parameter list illegal
main\streams/php_stream_transport.h(85) : error C2143: syntax error :
missing '{' before '*'
main\streams/php_stream_transport.h(86) : error C2059: syntax error : 'type'
main\streams/php_stream_transport.h(88) : error C2059: syntax error : ')'
main\streams/php_stream_transport.h(93) : error C2143: syntax error :
missing ')' before '*'
main\streams/php_stream_transport.h(93) : error C2081: 'socklen_t' :
name in formal parameter list illegal
main\streams/php_stream_transport.h(93) : error C2143: syntax error :
missing '{' before '*'
main\streams/php_stream_transport.h(94) : error C2059: syntax error : 'type'
main\streams/php_stream_transport.h(94) : error C2059: syntax error : ')'
main\streams/php_stream_transport.h(104) : error C2143: syntax error :
missing ')' before '*'
main\streams/php_stream_transport.h(104) : error C2081: 'socklen_t' :
name in formal parameter list illegal
main\streams/php_stream_transport.h(104) : error C2143: syntax error :
missing '{' before '*'
main\streams/php_stream_transport.h(105) : error C2059: syntax error :
'type'
main\streams/php_stream_transport.h(105) : error C2059: syntax error : ')'
main\streams/php_stream_transport.h(110) : error C2146: syntax error :
missing ')' before identifier 'addrlen'
main\streams/php_stream_transport.h(110) : error C2081: 'socklen_t' :
name in formal parameter list illegal
main\streams/php_stream_transport.h(110) : error C2061: syntax error :
identifier 'addrlen'
main\streams/php_stream_transport.h(110) : error C2059: syntax error : ';'
main\streams/php_stream_transport.h(110) : error C2059: syntax error : ','
main\streams/php_stream_transport.h(110) : error C2059: syntax error : ')'
main\streams/php_stream_transport.h(148) : error C2061: syntax error :
identifier 'socklen_t'
main\streams/php_stream_transport.h(152) : error C2059: syntax error : '}'
main\streams/php_stream_transport.h(157) : error C2061: syntax error :
identifier 'socklen_t'
main\streams/php_stream_transport.h(163) : error C2059: syntax error : '}'
main\streams/php_stream_transport.h(164) : error C2059: syntax error : '}'
************************************* END **********************

I'll try to see in sources tomorrow.

Ciao.
Mimmo.