Browsing through my 2nd-degree connections on LinkedIn, I noticed a recruiter who works for a company I'm particularly interested in. I don't know this recruiter at all, personally, but I do have a connection to them via a colleague from a previous job. I think it may be beneficial for me to connect with this recruiter, but I'm a bit concerned about asking for an introduction.
Unfortunately, I haven't been in touch with my former colleague in quite some time. This is not due to any ill regard for one another that I'm aware of. We just were never particularly close socially, and so did not make much effort to stay in touch after our paths diverged.
I also have never reached out to anyone via LinkedIn (or otherwise, for that matter) to request an introduction like this. So, I'm concerned about general matters of etiquette in that regard.
How should I go about doing this, so that it is well-received and effective? Are there any particular faux pas to be avoided? Might it actually be rude of me to ask for something like this, after not having contact for so long?