diff --git a/man/systemd.link.xml b/man/systemd.link.xml index bb4cd227e6b..cc55b02b182 100644 --- a/man/systemd.link.xml +++ b/man/systemd.link.xml @@ -468,15 +468,22 @@ must either be unset, empty, disabled, or all policies configured there must fail. Also see the example below with Name=dmz0. - Note that specifying a name that the kernel might use for another - interface (for example eth0) is dangerous because the - name assignment done by udev will race with the assignment done by the - kernel, and only one interface may use the name. Depending on the order of - operations, either udev or the kernel will win, making the naming - unpredictable. It is best to use some different prefix, for example - internal0/external0 or - lan0/lan1/lan3. - + Note that specifying a name that the kernel might use for another interface (for example + eth0) is dangerous because the name assignment done by udev will race with the + assignment done by the kernel, and only one interface may use the name. Depending on the order of + operations, either udev or the kernel will win, making the naming unpredictable. It is best to use + some different prefix, for example internal0/external0 or + lan0/lan1/lan3. + + Interface names must have a minimum length of 1 character and a maximum length of 15 + characters, and may contain any 7bit ASCII character, with the exception of control characters, + :, / and %. While . is + an allowed character, it's recommended to avoid it when naming interfaces as various tools (such as + resolvconf1) use + it as separator character. Also, fully numeric interface names are not allowed (in order to avoid + ambiguity with interface specification by numeric indexes), as are the special strings + ., .., all and + default. @@ -497,6 +504,12 @@ If the empty string is assigned to this option, the list is reset, and all prior assignments have no effect. If the kernel does not support the alternative names, then this setting will be ignored. + + Alternative interface names may be used to identify interfaces in various tools. In contrast + to the primary name (as configured with Name= above) there may be multiple + alternative names referring to the same interface. Alternative names may have a maximum length of + 127 characters, in contrast to the 15 allowed for the primary interface name, but otherwise are + subject to the same naming constraints.