Monthly Archives: March 2017

Fixing Postfix error unknown user name value: nobody

System: RHEL 6.9

Just got complain from App support Postfix was error.
Check on /var/log/maillog show this error
postfix[2319]: fatal: file /etc/postfix/ parameter default_privs: unknown user name value: nobody

The solution I did,check on /etc/passwd and found the user nobody in comment state.
Uncomment nobody and Postfix can start again.

# vi /etc/passwd
Uncomment nobody

# service postfix restart

Set up sysctl variables on CentOS/RHEL

A sysctl variable represents file locations under the /proc/sys directory. The dot(“.”) notation is used when setting in a configuration file.

– Set a sysctl parameter value immediately (not persistent/not applied on boot) on any version of RHEL:
Use the sysctl -w command. Parameter which take multiple values should have the values enclosed in quotes. For example, to set net.ipv4.ip_forward to 1 and net.ipv4.ip_local_port_range to 1025-65535:

# sysctl -w net.ipv4.ip_forward=1
# sysctl -w net.ipv4.ip_local_port_range="1025 65535"

Alternatively, it is possible to echo values directly into the procfs file which represents a sysctl parameter:

# echo 1 > /proc/sys/net/ipv4/ip_forward
# echo "1025 65535" > /proc/sys/net/ipv4/ip_local_port_range

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