User agent "-" (null)

Are there any legitimate agents that use "-" (null) only?

[seifried]

I've noticed that Nimda and several other user agents basically do not send a user agent string, I'm wondering if there are any legitimate clients that do this, I suspect the answer is no, but welcome feedback.

[Will]

Hi seifried,

Yes, there are quite a few that send empty or forged UA strings, several of which are from major search engines. Lycos and AOL are just two examples of "legitimate" forgers.

[littleman]

Will, could you show me a Lycos example? I've not seen it.

[Will]

littleman - below is a log excerpt:

2001-10-03 05:38:43 64.89.33.182 GET /robots.txt -
2001-10-03 05:38:43 64.89.33.182 GET /default.asp Lycos_Spider_(modspider)

Noticed this one a few times - typically it will check robots.txt with a blank UA, then adopt its normal id when checking subsequent pages.

First seen a few months ago inforum11/835.htm [webmasterworld.com].

[littleman]

Thanks for the info Will. I have bots visiting from that class C, but never without a UA.