IPv6 Network Administration

Remote Login Services

Remote login services are important, particularly for remote configuration of routers and other devices. We'll look at SSH and telnet, both of which are supported by IOS, JUNOS and most of the Unix-like systems we are looking at.

Telnetd

Like FTP, which has also been shipped with Unix-like systems for years, most vendors who ship IPv6 actually support telnet over IPv6, the main exception being some versions of Linux that shipped with an IPv4-only telnetd while generally supporting IPv6. The main gripe with telnet is that it may not encrypt the passwords sent for login, or even the data that is transferred subsequently. This could be rectified with IPsec, but in general ssh is now preferred.

SSH

OpenSSH has shipped with IPv6 support for a long time, so the Linux, BSD, and other vendors that use OpenSSH have mature support for IPv6. The only problem we've seen with OpenSSH was a bad interaction between the X11UseLocalhost option and IPv6, but this seems to have resolved itself. OpenSSH is available from http://www.openssh.com/.

Very little extra work is needed to offer SSH over IPv6. If you are using the ListenAddress directive, then you may want to also specify an IPv6 address, though by default OpenSSH will listen on both IPv4 and IPv6 addresses. Another place where addresses may be explicitly used is in the known_hosts file. If you manually maintain a known_hosts file, then you'll want to add corresponding IPv6 addresses where IPv4 addresses appear.

Solaris's ...