How to increase max username length?

UNIX for Advanced & Expert Users
1

Hi,
This is my first post to this site. So kindly forgive if I am writing in a wrong section.
My query is that...
I want to modify the max username length size. I guess it is 32/64 on CentOS. Now I want to change it to 128. Is there any way to do that?
Thanks in advance!! :slight_smile:

2

From the command line try:

getconf _POSIX_LOGIN_NAME_MAX  
#or 
getconf LOGIN_NAME_MAX

For a lot of reasons it is a really, really bad idea to try to exceed this value:
applications using (_POSIX_)LOGIN_NAME_MAX for usernames will segfault.
LDAP will not work.
Other PAM schemes will not work.
OpenSSH protocol 1 will fail with overlong usernames.
/etc/rhosts won't work for users on your box connecting to remote boxes

I don't think anything good will come from this but try editing /etc/default/login.defs.
CentOS follows Red Hat useradd conventions, see: /etc/default/useradd

3

Thanks a lot for ur reply, Jim :o
And, how can I increase the login name character limit in ftp?
Coz, I have noticed that when I use long login name(more than 20 character) to login using ftp command, it rejects my request.
I m very new to Unix. So please kindly tolerate my stupid questions :confused:

4

One way is to switch to using VSFTP. In the RHEL4 vsftpd package, the maximum username length was been increased to 128. For a while it dropped back to 32 characters (RHEL5 vsftpd-2.0.5-12.el5) but the regression was subsequently fixed.

5

Thanks:b: