Upgrade from v2.1 to v2.1a

Remount the disk read/write (remount w).
Make sure to rename or backup files that you have made
changes to (rc.local or similar) and is included in
this upgrade.

Copy the patch to /tmp and in the /tmp directory do:

tar Uzxpf /tmp/patch.21-21a.tar.gz

Adjust config files, restart daemons and remount the disk
read-only (remount r).

- - - - - - - - - - - - - - - - - - - - - - - - - - -
Added or changed files (included in the tar file):

-rw-------   1 root     root          340 Mar 29 13:27 ./boot/README
-r--------   1 root     root       547638 Mar 25 14:12 ./boot/vmlinuz.2.1.126fw
-r--------   1 root     root       547638 Mar 25 14:12 ./boot/vmlinuz.2.1.126rtr
-rwxr-----   1 root     filter       3023 Apr  1 09:41 ./default/example2/fwrules*
-rwxr-----   1 root     filter       1222 Apr  1 09:41 ./default/example2/fwrules.log*
-rwxr-----   1 root     filter        644 Apr  1 09:40 ./default/example2/fwrules.nis*
-rw-r-----   1 root     filter        141 Mar 24 13:44 ./default/example4/README
-rwxr-----   1 root     filter       1346 Mar 29 14:35 ./default/example4/fwrules*
-rwxr-----   1 root     filter        871 Mar 29 14:15 ./default/example4/fwrules.router*
-rwxr-----   1 root     filter        373 Mar 29 13:49 ./default/example4/fwrules.snmp*
-rwxr-----   1 root     filter        247 Mar 29 13:53 ./default/example4/fwrules.stat*
-rw-r--r--   1 root     root            6 Mar 24 14:45 ./etc/.version
-r--------   1 root     root          715 Apr  6 15:46 ./etc/config/.README
-r--------   1 root     root            3 Mar 31 14:33 ./etc/config/argus
-r--------   1 root     root            3 Mar 31 16:24 ./etc/config/atm
-r--------   1 root     root            4 Mar 31 14:15 ./etc/config/cron
-r--------   1 root     root            3 Mar 31 14:34 ./etc/config/dhcpd
-r--------   1 root     root            3 Mar 31 15:17 ./etc/config/dummy
-r--------   1 root     root            3 Apr  1 13:39 ./etc/config/full-router
-r--------   1 root     root            4 Apr  6 11:35 ./etc/config/fwrules
-r--------   1 root     root            3 Apr  1 13:39 ./etc/config/gated
-r--------   1 root     root            3 Apr  6 11:35 ./etc/config/inetd
-r--------   1 root     root            3 Apr  6 11:35 ./etc/config/iproute
-r--------   1 root     root            3 Mar 31 14:34 ./etc/config/lm78
-r--------   1 root     root            3 Mar 31 14:33 ./etc/config/ntp
-r--------   1 root     root            3 Mar 31 15:20 ./etc/config/proxy-arp
-r--------   1 root     root            3 Mar 31 14:14 ./etc/config/qos-test
-r--------   1 root     root            4 Mar 31 14:42 ./etc/config/slow-keyboard
-r--------   1 root     root            3 Mar 31 14:14 ./etc/config/snmpd
-r--------   1 root     root            4 Mar 31 14:15 ./etc/config/sshd
-r--------   1 root     root            4 Mar 31 14:49 ./etc/config/swedish-keyboard
-r--------   1 root     root            4 Mar 31 14:24 ./etc/config/tulip
-rw-------   1 root     root         1432 Apr  6 13:24 ./etc/lilo.conf
-rw-r--r--   1 root     root         1026 Apr  6 11:34 ./etc/ntp.conf
-r--------   1 root     root          161 Apr  6 15:51 ./etc/options/.README
-r--------   1 root     root          141 Apr  6 11:49 ./etc/options/nic.atm0
-r--------   1 root     root          133 Apr  6 11:32 ./etc/options/nic.dummy
-r--------   1 root     root           30 Apr  6 11:34 ./etc/options/ntp
-r-x------   1 root     root         2529 Apr  7 09:58 ./etc/rc.d/rc.M*
-r-x------   1 root     root         2194 Mar 31 14:49 ./etc/rc.d/rc.S*
-r-x------   1 root     root         3785 Apr  7 14:21 ./etc/rc.d/rc.inet*
-r-x------   1 root     root         1219 Mar 31 15:12 ./etc/rc.d/rc.local*
-r-x------   1 root     root          818 Apr  6 14:22 ./etc/rc.d/rc.nic.atm0*
-r-x------   1 root     root          377 Apr  6 14:20 ./etc/rc.d/rc.nic.dummy*
-r-x------   1 root     root          131 Apr  6 11:46 ./etc/rc.d/rc.nic.lo*
-r-x------   1 root     root          486 Apr  1 13:54 ./etc/rc.d/rc.ntp*
-r-x------   1 root     root          876 Apr  6 11:32 ./sbin/chkconfig*
-r-x------   1 root     root        26699 Apr  6 14:47 ./sbin/configure*
---x------   1 root     root      2221685 Apr  6 16:03 ./sbin/gated*
---x------   1 root     root       294611 Apr  6 16:02 ./sbin/pimd*
-r-x------   1 root     root         3014 Apr  6 14:16 ./sbin/setrouter*
-rw-r--r--   1 root     root          165 Mar 31 08:55 ./sbin/tulip.WARNING
-r--------   1 root     root        37672 Dec  3 15:39 ./sbin/tulip.o
-r--------   1 root     root        39436 Mar 30 13:27 ./sbin/tulip.planet.o
---x--x--x   1 root     root       552536 Mar 24 16:13 ./usr/bin/kermit*
---x------   1 root     root        22604 Apr  7 15:19 ./usr/sbin/klogd*
---x------   1 root     root        29416 Apr  7 15:18 ./usr/sbin/syslogd*
---x------   1 root     root       143796 Mar 30 14:16 ./usr/sbin/wu.ftpd*

Stuff that has been removed or must be changed by hand:

Check your rc files and other configs with the list above
to be sure to restore the accurate configuration.
A lot of configuration has been changed (moved) to the
/etc/options and /etc/config directories.
Make sure to set the following permissions:

chmod go-r /etc/config
chmod go-r /etc/options
chmod go-rx /.ssh

After that, remount disk to read/write and run:

configure
chkconfig

To set the IP-numbers, netmasks and other config.
When everything looks OK, reboot...