One can see from the recent discussion Correcting links with university proxy (especially MathSciNet links) that some users add in their posts links that only work for people behind a specific proxy, and that some other users spend time correcting those links.

This looks like a problem that can be solved automatically. I would suggest Stack Exchange to implement a check upon posting a question/answer: if a link coming from a specific blacklist of proxies is detected, a warning is shown ("This post may contain links to documents that are not visible by users outside your institution; do you wish to continue?")

• That's a good feature request, hopefully the fact there are several academic sites on the network will encourage the SE Overlords to implement it too. – Asaf Karagila Jul 21 '17 at 8:43
• If it turns out that we like this suggestion here, then it should be posted for discussion on the "big" stackexahnge meta. – Gerald Edgar Jul 21 '17 at 12:26
• Probably diamond users know more about this, but I think that it is already possible to add warnings triggered by certain strings or to blacklist them entirely. For example, see the list of blacklists and warnings on math.SE. However, if also rewrite of the link should be implemented, that would probably be a new feature. – Martin Sleziak Jul 22 '17 at 4:22

It could be reasonable to collect some past examples of such proxies. This would help in assessing whether something like this is technically feasible. (And maybe also to which extent implementing this might actually be useful.)

Also I assume that if something like this is implemented at some point, we'll need to prepare list of regular expressions for such automatic rewrites - so it is good which proxies we are concerned with. (The post is CW, feel free to add more examples.)

Typically the rewrite would look like this:

Some differently looking changes:

• I will be grateful also for suggestions about the format. Would it be better to omit the examples (or perhaps mention a few of them outside the list) and simply leave there number of occurrences together with a link to SEDE query listing them? – Martin Sleziak Dec 28 '18 at 15:30
• Martin, on behalf of many MO users, I would like to thank you for your outstanding work on this matter and many others. We all appreciate your efforts very much! – Joel David Hamkins Dec 29 '18 at 23:27
• That adelaide proxy link was due to me, and if you go look at the result, I had edited out the proxy link in a past revision; the data explorer seems to be picking up old versions of questions and answers. – David Roberts Dec 30 '18 at 1:13
• @DavidRoberts If you look at the query, it is on purpose that we are looking on occurrences in all past revisions. After all, the query is called: "Posts with given word in some of the revisions". This should be obvious also from the fact that links listed as examples are to past revisions. (Ideally all such links should be edited by now. Since Federico Poloni suggested some automation, it is good to know how many manual edits would be automated in this way.) – Martin Sleziak Dec 30 '18 at 2:59
• If somebody wants to find the occurrences that still exist, it's possible to use on site search. Of course, you can also use SEDE if you prefer. – Martin Sleziak Dec 30 '18 at 2:59
• And it is also possible to look also for all posts where given string was edited out. – Martin Sleziak Dec 30 '18 at 3:00
• @Martin ah, I see: to get a scope of the history of the problem, not just the current state. – David Roberts Dec 30 '18 at 8:17
• @DavidRoberts Yes, that was the intention. Even if the outcome of this will be that the problem is too minor to require some automated solution (at least at current size of MO site), at least the feature request is not left without a response. (As I have already mentioned in the comments under the question, if we want just some kind of warning triggered based on some regex detecting url containing a proxy, that's already possible. However, for this we would need some help from moderators.) – Martin Sleziak Dec 30 '18 at 11:07
• The UMich proxy has changed so that, instead of something like link.springer.com.proxy.lib.umich.edu , one gets link-springer-com.proxy.lib.umich.edu . (I see that this is consistent with the library.nd.edu and galib.uga.edu proxies.) – LSpice Dec 31 '18 at 17:07
• @LSpice Unless I missed something, so far this proxy was only used on this site in the "old form". Anyway, I have included the information from your comment into the post. – Martin Sleziak Jan 2 at 20:37

Let me add another suggestion how to handle this - with already existing tools, without any need to implement something new. (It is probably not worth to create a separate question for this - I am posting this suggestion as an answer, we'll see from the voting and the comments what MO users and moderators think about it.)

It is already possible to show various warnings depending on body, title and tags of the post. As far as I can tell, the warning is triggered depending on presence of some specific strings and it is possible to use regular expressions.1 From what I have seen in meta discussions, such warnings can be added by Stack Exchange staff. The request to do so quite often come from the mods, more often than not after some discussion on meta.

Proposal. I think that it should not be difficult to create a regex to find out whether a post contains an url containing the string proxy. In such case, a warning should be shown (with a short explanation that such links could be a possible problem and suggesting to the poster to check the links).

Disadvantages. This will create some false positives - which is the reason why I do not suggest to blacklist such input, just to show a warning. Also some users will probably ignore the warning - in such cases we have to rely on the fact that somebody notices the post and corrects the link.

Advantages. It is probably easier to create a check which might return some false positives but which should definitely catch most of the problematic links. (I would definitely consider this better than creating a separate regular expression for each proxy - assuming the numbers in the CW answer are close to correct, then by creating a regular expression which in some way handles a specific proxy we would help with at most 5 posts. I don't think that this is worth the effort - MO would need for each specific proxy go through moderators and ask somebody from Stack Exchange to add it to the list.) Unless there is some way which would take care of many proxies at the same time - which seems unlikely to me - this seems to me much simpler solution than trying to implement some way to automatically rewrite such links, considering the number of posts where this is actually a problem.

1If I find some place where this is documented in detail, I can add it here. The best I can provide at the moment is the list on Mathematics Meta. As you can see, it contains also some regular expressions.