1 Linux Valid Usernames

tengel edited this page 2024-03-20 11:55:03 -05:00

POSIX Standard

• https://pubs.opengroup.org/onlinepubs/009695399/basedefs/xbd_chap03.html#tag_03_426
• https://pubs.opengroup.org/onlinepubs/009695399/basedefs/xbd_chap03.html#tag_03_276

Upstream Source

• https://github.com/shadow-maint/shadow/blob/master/libmisc/chkname.c

Debian Family

• https://salsa.debian.org/debian/shadow/blob/master/debian/patches/506_relaxed_usernames

/*
 * POSIX indicate that usernames are composed of characters from the
 * portable filename character set [A-Za-z0-9._-], and that the hyphen
 * should not be used as the first character of a portable user name.
 *
 * Allow more relaxed user/group names in Debian -- ^[^-~+:,\s][^:,\s]*$
 */

RHEL Family

• https://src.fedoraproject.org/cgit/rpms/shadow-utils.git/tree/shadow-4.5-goodname.patch

/*
 * User/group names must match gnu e-regex:
 *    [a-zA-Z0-9_.][a-zA-Z0-9_.-]{0,30}[a-zA-Z0-9_.$-]?
 *
 * as a non-POSIX, extension, allow "$" as the last char for
 * sake of Samba 3.x "add machine script"
 *
 * Also do not allow fully numeric names or just "." or "..".
 */

---

BSD Family

OpenBSD

• https://cvsweb.openbsd.org/src/usr.sbin/user/user.c?rev=1.123&content-type=text/x-cvsweb-markup

FreeBSD

• https://github.com/freebsd/freebsd/blob/master/usr.sbin/pw/pw_user.c

NetBSD

• http://cvsweb.netbsd.org/bsdweb.cgi/src/usr.sbin/user/user.c?rev=1.132&content-type=text/x-cvsweb-markup&only_with_tag=MAIN

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