I need an always ON service!!

[Enrico Venturi]

Hello colleagues,
for security reasons the system platform administrator decided to inhibit all the following services:
1. R command functionality:
1. rlogin
2. remsh
3. rcp
4. rwho
5. rpc.cmsd
6. rpcbind
7. rexec
2. FTP
3. TFTP
4. Network File System (NFS).
5. Traceroute
6. Finger and talk applications.
7. Echo (udp/tcp)
8. Chargen (tcp)
9. Time (tcp)
10. Daytime (tcp)
11. SNMP Agent

Unfortunately I have an application which check for the alive status of the machines by connecting to a certain port, currently the port 13, which is being disabled.
Are there any services always running but the previous listed ones?
Thanks a lot

Enrico

[Rodney Hills · Accepted solution]

Port 22 is used by secure shell "ssh".

HTH

-- Rod Hills

[Jeff Schussele]

Ciao Enrico,

Try SSH port - 22 TCP
and/or telnet port - 23 TCP

HTH,
Jeff

[Tomek Gryszkiewicz]

It depends on the system, and what for it's used - i think you should ask you administrator. But, if you are testing the open ports, try maybe this:
25 - sendmail
80 - http
22 - sshd
Or just ping the machine instead of opening the connection to it.

-Tomek

[Jeff Schussele]

You might also consider NTP - Network Time Protocol - 123 UDP

Cheers,
Jeff

[Fred Ruffet]

printer (515/tcp) and X11 (6000/tcp) may also be running services.

Regards,

Fred

[Armin Kunaschik]

The list looks quite incomplete... from the security point of view.
I'm missing for instance telnet and sendmail.
Get a list of open ports and services with
"netstat -a" and lsof.
But that's not the point!

You should define a state where you consider the machine alive!
Monitoring port 13 (daytime) does not tell you that your application is alive.
It only tells you that the kernel answers network queries.
You can even ping your machine. But the result is: The host responds to icmp queries. Not more!

Monitor your application instead of unnecessary ports, e.g. frequently get http pages, issue sql queries etc.!!

Hope this helps,
Armin