| Adobe: Security bulletins and technical briefs that provide information to customers. |
| AIX: Security and other patches for AIX. Note that this is an FTP site. |
| AIX Patches - Fixdist: You need the "fixdist" program to install AIX patches. |
| Apache Web Server: Advisories and patches. |
| Cisco: Patches and advisories for Cisco products |
| Citrix: Security bulletins and hotfixes for Citrix products |
| Compaq: Patches and advisories for most Compaq products. |
| Debian: Security Information: Details of current and archive security advisories. Includes mailing list and a security FAQ. |
| FreeBSD: Advisories, mailing lists, tips, tricks, guidelines, links. |
| FreeBSD Patches FTP Site: Security advisories and patches. |
| HP-UX Patch Additional Information: Patch Security Matrix, list of obsolete patches, patch checksums. |
| HP: IT Resource Center: Americas/Asia-Pacific site offering online support. Includes knowledge base, patches, drivers and security mailing lists. |
| HP: Tru64 Unix: Security advisories and associated patches. |
| KDE: Only if you've built KDE yourself; otherwise probably available from your linux distribution vendor's patches directory. Note this is an FTP site. |
| Microsoft: Download security updates, service packs, and anti-spyware tools for Windows. |
| Microsoft Security: Microsoft-product-related security headlines and bulletins. |
| NetBSD: Security patches for all releases. Note this is an FTP site. |
| NetBSD: Advisories, patches, links. |
| Netscape: Security alerts for netscape client and server software. |
| OpenBSD Release Errata: Advisories and patches. |
| OpenBSD Security: Advisories and information. |
| Oracle: Patches and other security information. |
| Red Hat Linux Errata: Security advisories and updates (patches) for all supported versions. |
| Red Hat Linux Security Resource Center: Alerts, whitepapers, articles, presentations, and tools. |
| SCO: Security information for Caldera OpenLinux, OpenServer, OpenUnix, and UnixWare. |
| SCO Unix System Security Enhancement Area: Advisories and patches. Note this is an FTP site. |
| SGI: IRIX: Security advisories and patch downloads. Includes mailing list. |
| Sun Microsystems: Security and recommended patches for Solaris: patch clusters and individual patches. |
| SuSE Linux: Patches directories for all supported versions, plus a security announcements list (English). |
Classical
