Proxy chains force any tcp connection made by any given tcp client to follow through proxy (or proxy chain). it is a kind of proxifier. it acts like sockscap / premeo / eborder driver ( intercepts tcp calls )

see 'proxychains' package for more detailed description.

this package contains runtime for the shared library used by proxychains.

the package 'dnsutils' is needed to perform dns requests through proxy. in the case you turned 'proxy_dns' option off in configuration file you don't need dnsutils to be installed.