ipsec showhostkey - show host's authentication key

ipsec showhostkey [ --key ] [ --left ] [ --right ] [ --txt gateway ] [ --dhclient ] [ --file secretfile ] [ --id identity ]

Showhostkey outputs (on standard output) a public key suitable for this host, in the format specified, using the host key information stored in /etc/ipsec.secrets. In general only the super-user can run this command, since only he can read ipsec.secrets.

The --txt option causes the output to be in opportunistic-encryption DNS TXT record format, with the specified gateway value. If information about how the key was generated is available, that is provided as a DNS-file comment. For example, --txt 10.11.12.13 might give (with the key data trimmed for clarity):

  ; RSA 2048 bits   xy.example.com   Sat Apr 15 13:53:22 2000
      IN TXT  "X-IPsec-Server(1)=10.11.12.13 AQOF8tZ2...+buFuFn/"

No name is supplied in the TXT record because there are too many possibilities, depending on how it will be used. If the text string is longer than 255 bytes, it is split up into multiple strings (matching the restrictions of the DNS TXT binary format). If any split is needed, the first split will be at the start of the key: this increases the chances that later hand editing will work.

The --left and --right options cause the output to be in ipsec.conf(5) format, as a leftrsasigkey or rightrsasigkey parameter respectively. Again, generation information is included if available. For example, --left might give (with the key data trimmed down for clarity):

  # RSA 2048 bits   xy.example.com   Sat Apr 15 13:53:22 2000
  leftrsasigkey=0sAQOF8tZ2...+buFuFn/

The --dhclient option cause the output to be suitable for inclusion in dhclient.conf(5) as part of configuring WAVEsec. See <http://www.wavesec.org>.

If --key is specified, the output format is the text form of a DNS KEY record; the host name is the one included in the key information (or, if that is not available, the output of hostname --fqdn), with a . appended. Again, generation information is included if available. For example (with the key data trimmed down for clarity):

  ; RSA 2048 bits   xy.example.com   Sat Apr 15 13:53:22 2000
  xy.example.com.   IN   KEY   0x4200 4 1 AQOF8tZ2...+buFuFn/

Normally, the default key for this host (the one with no host identities specified for it) is the one extracted. The --id option overrides this, causing extraction of the key labeled with the specified identity, if any. The specified identity must exactly match the identity in the file; in particular, the comparison is case-sensitive.

The --file option overrides the default for where the key information should be found, and takes it from the specified secretfile.

A complaint about ``no pubkey line found'' indicates that the host has a key but it was generated with an old version of FreeS/WAN and does not contain the information that showhostkey needs.

/etc/ipsec.secrets

ipsec.secrets(5), ipsec.conf(5), ipsec_rsasigkey(8)

Written for the Linux FreeS/WAN project <http://www.freeswan.org> by Henry Spencer.

Arguably, rather than just reporting the no-IN-KEY-line-found problem, showhostkey should be smart enough to run the existing key through rsasigkey with the --oldkey option, to generate a suitable output line.

The need to specify the gateway address (etc.) for --txt is annoying, but there is no good way to determine it automatically.

There should be a way to specify the priority value for TXT records; currently it is hardwired to 10.

The --id option assumes that the identity appears on the same line as the : RSA { that begins the key proper.