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md5 collision

September 13, 2012 07:07AM
Hi,
Looking for help with a high number of md5 collisions with proxy caching. It's my understanding that we shouldn't be getting any, but we seem to be getting quite a few.

-V
nginx version: nginx/1.2.3
built by gcc 4.6.3 (Ubuntu/Linaro 4.6.3-1ubuntu5)
configure arguments: --prefix=/opt/nginx --with-http_stub_status_module --with-pcre=../pcre-8.31 --without-http_access_module --without-http_auth_basic_module --without-http_autoindex_module --without-http_browser_module --without-http_charset_module --without-http_fastcgi_module --without-http_geo_module --without-http_memcached_module --without-http_referer_module --without-http_scgi_module --without-http_split_clients_module --without-http_ssi_module --without-http_upstream_ip_hash_module --without-http_userid_module --without-http_uwsgi_module --add-module=../agentzh-headers-more-nginx-module-278ba7d --conf-path=nginx.conf --error-log-path=/var/log/nginx/error.log --http-log-path=/var/log/nginx/access.log --with-debug

I believe this might be relevant as well:


checking for system md library ... not found
checking for system md5 library ... not found
checking for OpenSSL md5 crypto library ... found
checking for zlib library ... found
creating objs/Makefile

Configuration summary
+ using PCRE library: ../pcre-8.31
+ OpenSSL library is not used
+ md5: using system crypto library
+ sha1 library is not used
+ using system zlib library


We are using the default cace key, though I've tried a few variations. We are doing one "weird" thing...The upstream server might re-request a slightly modified version from Nginx in the hopes that this modified version is in the cache. If it isn't, this modified request goes back to the upstream, which then returns a file (which then goes back to the upstream to fulfill the original request). At most, this is 2 loops... NGINX --> Upstream --> NGINX --> Upstream but the URLs wil be different between the first set and the second one. Not sure that this is a problem, but since it's the only odd thing, I figured I'd mention it.

Cheers,
Karl
Subject Author Posted

md5 collision

karlseguin September 13, 2012 07:07AM

Re: md5 collision

Maxim Dounin September 13, 2012 08:50AM

Re: md5 collision

karlseguin September 13, 2012 11:21AM

Re: md5 collision

Maxim Dounin September 13, 2012 04:16PM

Re: md5 collision

karlseguin September 13, 2012 07:43PM

Re: md5 collision

Maxim Dounin September 14, 2012 07:16AM



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