The issue was that I cannot change my security level setting at all.

I am using a redhat linux 8.0 system. I tried to do it with GUI through system setting --> security level --> no firewall, then gettting a warning message to ask cancel or ok, I clicked ok and it seems that the system accepts it but it turns out it did not really remember the change. It always gives me the "high" security level setting.

I also tried to use command "redhat-config-securitylevel", basically it gave me the same window interface as I had above. Finally, it did not remember what I changed, so basically I cannot change the security level setting at all.

I also tried "lokkit", selecting "none firewall", then "ok", but it still cannot be changed. When you run lokkit again, it always gave you the "high" level.

I really need to change the security level to none, in order to insall Matlab, whose installation cannot be finished without turning off the security level to none in my linux system.

However, I really need the matlab working to finish my project.

I would really appreciate it if anybody here could help me out.

Thanks.

David

Are you running it as root? That might help.

IIRC, that was sort of a bug (or feature depending on your point of view), where the GUI always displayed the sec level as set to "high" whenever you opened it. The rationale being that it would encourage users to set it to high. If you change the level and apply it, then the changes *WILL* still take effect. To verify, as root run: iptables -vnL

Thanks. I did run as root...

Thanks for your advice. I ran what you suggested and got the following:

[root@localhost etc]# iptables -vnL
Chain INPUT (policy ACCEPT 447 packets, 37896 bytes)
pkts bytes target prot opt in out source destination

Chain FORWARD (policy ACCEPT 0 packets, 0 bytes)
pkts bytes target prot opt in out source destination

Chain OUTPUT (policy ACCEPT 416 packets, 41110 bytes)
pkts bytes target prot opt in out source destination


I am still new to Linux. I have no idea on what the above mean to my problem.

Thanks.

It looks like all your chains are set to accept all traffioc, so there are no firewall rules blocking anything.

Thanks. You meant my system does not have any security or firewall? But I cannot still finish my matlab installation (I just tried that again).

No, your Matlab installation issue doesn't belong in the Linux Security forum and listing it *knowing* it doesn't belong here is close to crossposting so please edit your post and remove that.