The remote host is missing an update to quagga announced via advisory USN-775-1.
Details follow:
It was discovered that the BGP service in Quagga did not correctly handle certain AS paths containing 4-byte ASNs. An authenticated remote attacker could exploit this flaw to cause bgpd to abort, leading to a denial of service.
Solution: The problem can be corrected by upgrading your system to the following package versions:
Ubuntu 6.06 LTS: quagga 0.99.2-1ubuntu3.5
Ubuntu 8.04 LTS: quagga 0.99.9-2ubuntu1.2
Ubuntu 8.10: quagga 0.99.9-6ubuntu0.1
Ubuntu 9.04: quagga 0.99.11-1ubuntu0.1
In general, a standard system upgrade is sufficient to effect the necessary changes.