How To Use netcat and telnet for Simple Network Testing

Author: , January 27th, 2015

yum install nc SERVER-SIDE: host1 shell> echo hello | nc -l 3456 CLIENT-SIDE: host2 shell> nc host1 3456 hello ~or~ CLIENT-SIDE: yum install telnet host1 shell> telnet host2 {PORT}

How To Setup A Smart Relay Host Port on Sendmail

Author: , January 26th, 2011

Configure the Smart Host Search for DS in /etc/mail/sendmail.cf and edit as follows: Before: DS After: DSyour.mail.relay.yourdomain.com Configure The Port Search for Mrelay and edit as follows: Before: Mrelay, P=[IPC], F=mDFMuXa8, S=EnvFromSMTP/HdrFromSMTP, R=MasqSMTP, E=\r\n, L=2040, T=DNS/RFC822/SMTP, A=TCP $h After: Mrelay, P=[IPC], F=mDFMuXa8, S=EnvFromSMTP/HdrFromSMTP, R=MasqSMTP, E=\r\n, L=2040, T=DNS/RFC822/SMTP, A=TCP $h 2525 Add the following line appropriately […]

How To Configure PostFix To Listen On Multiple Ports

Author: , November 27th, 2010

Modify /etc/postfix/master.cf, and add one line per port. The example below shows the original smtp line along with a sample new line. 25 inet n – – – – smtpd 2525 inet n – – – – smtpd Make sure to open the port in your firewall… Another interesting solution I found was to use […]