Bugtraq mailing list archives
Re: SMTP server account probing
From: Valdis.Kletnieks () VT EDU (Valdis.Kletnieks () VT EDU)
Date: Tue, 9 Mar 1999 16:08:32 -0500
--==_Exmh_-10015426P Content-Type: text/plain; charset=us-ascii On Tue, 09 Mar 1999 09:36:04 PST, you said:
Perhaps someone with better sendmail experience could come up with an idea to automatically disconnect connections that are issuing more than 25 VRFY statements at a time?
Wrong solution. They'll just reconnect and try another 25. All you've bought then is an extra fork() of the sendmail daemon every 25 pokes. Remember, these people don't give a s**t if they waste your resources... Maybe what's needed is a new ioctl on a socket, so you can do this: if (vrfy_cnt > 25) { ioctl(net_socket,SO_NOSENDFIN); clkose(net_socket); } so you can free up the socket at YOUR end, and intentionally fail to send the FIN packet, so the OTHER end gets to wait for a timeout. Yes, yes, yes, I *KNOW* it's Evil and Against The RFCs. But it's tempting. ;) -- Valdis Kletnieks Computer Systems Senior Engineer Virginia Tech --==_Exmh_-10015426P Content-Type: application/pgp-signature -----BEGIN PGP MESSAGE----- Version: 2.6.2 iQCVAwUBNuWNz9QBOOoptg9JAQGKugQAvrh/JXICvFpWsu5oGH9RH0JXx9SheZJL PbzBVg2OPouPHvqG3UU012nJj8489OJ79a4kLpFDGYERjScrNqxnU5QdMqlr+GXV SFNRGV/AqigZEFkf1/GEvnluTDX1KdaXb98pAKE9Ni664F4NyhQaYNcbY4JBJT6T m7m9DJmYjdI= =MPrZ -----END PGP MESSAGE----- --==_Exmh_-10015426P--
Current thread:
- SMTP server account probing Brett Glass (Mar 08)
- Re: SMTP server account probing Frank Miller (Mar 09)
- Re: SMTP server account probing John E. Martin (Mar 09)
- Re: SMTP server account probing Brett Glass (Mar 09)
- Re: SMTP server account probing Nick Andrew (Mar 09)
- Re: SMTP server account probing Brian Behlendorf (Mar 09)
- Re: SMTP server account probing Valdis.Kletnieks () VT EDU (Mar 09)
- Re: SMTP server account probing Scott Fendley (Mar 09)
- Re: SMTP server account probing Alexander Bochmann (Mar 10)
- Re: SMTP server account probing Alan Cox (Mar 09)
- Re: SMTP server account probing Brett Glass (Mar 09)
- Re: SMTP server account probing Ryan Permeh (Mar 09)
- Re: SMTP server account probing Keith Woodworth (Mar 09)
- Linux Blind TCP Spoofing Security Research Labs (Mar 09)
- Re: Linux Blind TCP Spoofing John D. Hardin (Mar 09)
- Winfreeze.c for Solaris ... Max Schubert (Mar 09)
- Re: SMTP server account probing GvS (Mar 09)
- Re: SMTP server account probing David Gale (Mar 09)