I came across some web hosts offering proxy site hosting under a shared account. But I suggest you get at least a VPS account because proxy sites are resource hungry .
Shoudn't beeee allowed as such sites mask the identity of the actual user and these type of sites are usually a source of illegal activity.
So you allow them on dedicated servers?
We allow private proxies only. Public proxies are not allowed and if we get any complaints for any of our servers allowing open proxies then we suspend that particular server.