On Tue, 12 Jul 2005, Ian FREISLICH wrote:

> Out of interest what proportion of your logs have useful ident data?

Depends what you mean by "useful".

I give you these, for example:

2005-07-06 22:51:54 H=(corporation.net) [168.187.205.3] U=CacheFlow Server 
F=<[EMAIL PROTECTED]> rejected RCPT 
Rejected - appears to be an unsecured proxy: CacheFlow Server

2005-07-07 18:03:25 H=(mailhub.vianetworks.nl) [194.250.136.80] 
U=squid F=<[EMAIL PROTECTED]> rejected RCPT 
Rejected - appears to be an unsecured proxy: squid

There's still (years after this problem was first exposed) a moderate 
number of such rejections in our log.  In due course the IPs in 
question turn up in blacklists (and indeed both of those IPs are well 
and truly blacklisted now), and could be rejected on that or on other 
grounds, but these characteristic idents seem to be a sure-fire 
rejection, on the assumption that no-one is seriously going to run 
their MTA with a user name of "squid", let alone "CacheFlow Server".

Sure, the original motive was multi-user systems, where individual 
users might be attempting direct-to-MX SMTP, and I'd admit that this 
scenario is far less usual than it used to be, for many different 
reasons.  But when reporting abuse to some remote site, it can still 
be a useful handle.

Whether you choose to activate ident or not is entirely a matter for 
your local policy, and I wouldn't for a moment try to tell you what to 
do.  But if you do activate it, then definitely set the timeout to 
just a few seconds (we've used 7s for a considerable time, but I 
suspect it could well be less and still serve its purpose).  Ideally, 
if a remote network is not going to respond to ident then it should 
reject, rather than dropping the traffic on the floor and leaving us 
to time out, but that isn't something we have any control over, 
obviously.

best regards

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