4,387 reputation
612
bio website systemajik.com
location Gatineau, Canada
age 59
visits member for 3 years, 10 months
seen 1 hour ago
I have over 30 years experience in all phases of software development and delivery. I have administered a variety of midrange servers, and worked with systems from PCs to Mainframes.

Nov
8
comment Disable user shell for security reasons
Some email systems allow use of their own password mechanisms. I use Dovecot and Exim with an email only password. This allows use of webmail on servers I would not use my system password. Virtual email domains require their own password as they aren't coupled to the servers password system.
Nov
2
revised Unable to ssh out from my laptop
Add more information.
Nov
2
revised Unable to ssh out from my laptop
Add more information.
Nov
2
comment Unable to ssh out from my laptop
traceroute -T --port 22 would work also, but by default requires root access. tcptraceroute works without root access.
Nov
2
answered Unable to ssh out from my laptop
Oct
13
comment How do I find out if I am sudoer?
Your password for sudo is your login password. sudo will ask for your password to verify it is you checking. Passwords are usually remembered for a few minutes if you are few minutes.
Sep
21
awarded  Custodian
Sep
8
answered Why updating a running Linux system is not problematic?
Jul
31
comment Problems setting up web server in CentOS
@bev The <Directory /> could allow access but it is more secure for it to deny from all. The /var/www should match the directory specified as your site's DocumentRoot.
Jul
27
answered Problems setting up web server in CentOS
Jul
21
revised Is there any reason to have ntpd sync to Local(0) if server is not used as a time source?
added 237 characters in body; added 126 characters in body
Jul
21
answered Is there any reason to have ntpd sync to Local(0) if server is not used as a time source?
Jul
20
awarded  Critic
Jul
20
comment Is there any reason to have ntpd sync to Local(0) if server is not used as a time source?
Most systems have at least a Time of Year (TOY) clock. While not as accurate as other sources, but usually relatively accurate. It should be fudged to a high stratum as shown so it is only used as a last resort.
Jul
17
comment Run unix command precisely at very short intervals WITHOUT accumulating time lag over time
At various times of the day the system is likely to be quite busy, and unless you use a real-time priority you will get slippage. The busier the system the more slippage to expect.
Jul
3
comment IPv6 in IPv4 over LAN
Not on my network. The only valid incoming addresses on the external network are my external addresses. Likewise for valid sources outgoing.
Jul
2
comment IPv6 in IPv4 over LAN
Route filtering?
Jul
2
comment IPv6 in IPv4 over LAN
@bahamat I am fully aware that fixed NAT does not provide any security. The use of private (non-Internet routeable) addresses does provide security in the absence of any incoming NAT rules. The stateful source NAT typically used for IP masquerading in this case tends to be secure, and to the best of my knowledge is not Linux specific. Firewalling does not provide private addesses access to the Internet, NAT does. I'll leave it at that.
Jul
2
comment IPv6 in IPv4 over LAN
@bahamat I think you are confusing connection tracking for a IP Masquerading (which enables hosts on private addresses to connect to the Internet) with connection tracking for firewalling. IP Masquerading is not firewalling, but both can use the same connection tracking data. DNAT which is not IP Masquerading can be used to pass in through the firewall.
Jun
30
comment IPv6 in IPv4 over LAN
@bahamat On the stateful NAT configurations I have used if you can craft the right packets, you are likely already passing through. The firewall further limits which port can pass in or out.