Hello dear List Members. One of our SuSE 8.0 boxes which is a sendmail mailserver got those lines in /var/log/mail:
Jun 2 01:26:12 suse80box sendmail[18268]: h51LQCu5018268: [XXX.YYY.ZZZ.TTT] did not issue MAIL/EXPN/VRFY/ETRN during connection to MTA Jun 2 01:26:13 suse80box sendmail[18270]: h51LQDu5018270: [XXX.YYY.ZZZ.TTT] did not issue MAIL/EXPN/VRFY/ETRN during connection to MTA Jun 2 01:26:14 suse80box sendmail[18272]: h51LQEu5018272: [XXX.YYY.ZZZ.TTT] did not issue MAIL/EXPN/VRFY/ETRN during connection to MTA Jun 2 01:26:18 suse80box sendmail[18274]: h51LQFu5018274: [XXX.YYY.ZZZ.TTT] did not issue MAIL/EXPN/VRFY/ETRN during connection to MTA Jun 2 01:26:20 suse80box sendmail[18276]: h51LQJu5018276: [XXX.YYY.ZZZ.TTT] did not issue MAIL/EXPN/VRFY/ETRN during connection to MTA Jun 2 01:26:21 suse80box sendmail[18278]: h51LQKu5018278: [XXX.YYY.ZZZ.TTT] did not issue MAIL/EXPN/VRFY/ETRN during connection to MTA Jun 2 01:26:22 suse80box sendmail[18280]: h51LQMu5018280: [XXX.YYY.ZZZ.TTT] did not issue MAIL/EXPN/VRFY/ETRN during connection to MTA Jun 2 01:26:23 suse80box sendmail[18282]: h51LQNu5018282: [XXX.YYY.ZZZ.TTT] did not issue MAIL/EXPN/VRFY/ETRN during connection to MTA Jun 2 01:26:24 suse80box sendmail[18284]: h51LQOu5018284: [XXX.YYY.ZZZ.TTT] did not issue MAIL/EXPN/VRFY/ETRN during connection to MTA Jun 2 01:26:28 suse80box sendmail[18286]: h51LQSu5018286: [XXX.YYY.ZZZ.TTT] did not issue MAIL/EXPN/VRFY/ETRN during connection to MTA Jun 2 01:26:29 suse80box sendmail[18288]: h51LQTu5018288: [XXX.YYY.ZZZ.TTT] did not issue MAIL/EXPN/VRFY/ETRN during connection to MTA Jun 2 01:26:30 suse80box sendmail[18290]: h51LQUu5018290: [XXX.YYY.ZZZ.TTT] did not issue MAIL/EXPN/VRFY/ETRN during connection to MTA Jun 2 01:26:31 suse80box sendmail[18292]: h51LQVu5018292: [XXX.YYY.ZZZ.TTT] did not issue MAIL/EXPN/VRFY/ETRN during connection to MTA
I've googled for those and found some situations involving port scans etc. But here we get the messages every second so this should be a DoS attempt. Am I right? What is the medicine? -- Best regards, Boris Kimel mailto:bobk@ioc.ac.ru