IPSEC with OpenBSD

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Intro

Stage a few Machines, puffy206 - 209 puffy206 has got a static ip, while puffy207 - 209 got dynamic ip addresses

Master, puffy206

Loopback

doas su -
cat << 'EOF' > /etc/hostname.lo1
inet 10.0.0.6/32
up
EOF

Enable IPSEC & IP Forwarding

cat << 'EOF' >> /etc/sysctl.conf
net.inet.ip.forwarding=1
net.inet.gre.allow=1
EOF

rcctl enable ipsec isakmpd
rcctl set isakmpd flags -K

Create Tunnel Endpoint

cat << 'EOF' > /etc/ipsec.conf
ike dynamic esp tunnel from 10.0.0.6/32 to 10.0.0.7/32 peer any \
    main group "modp1024" quick group "modp1024" \
    psk "my-tunnel-is-private"

ike dynamic esp tunnel from 10.0.0.6/32 to 10.0.0.8/32 peer any \
    main group "modp1024" quick group "modp1024" \
    psk "my-tunnel-is-private"

ike dynamic esp tunnel from 10.0.0.6/32 to 10.0.0.8/32 peer any \
    main group "modp1024" quick group "modp1024" \
    psk "my-tunnel-is-private"
EOF
chmod 600 /etc/ipsec.conf

Reboot and Check

reboot
gnuwatch "ipsecctl -s all"

Slave, puffy207

Loopback

doas su -
cat << 'EOF' > /etc/hostname.lo1
inet 10.0.0.7/32
up
EOF

Enable IPSEC & IP Forwarding

cat << 'EOF' >> /etc/sysctl.conf
net.inet.ip.forwarding=1
net.inet.gre.allow=1
EOF

rcctl enable ipsec isakmpd
rcctl set isakmpd flags -K

IPSEC

cat << 'EOF' > /etc/ipsec.conf
ike esp tunnel from 10.0.0.7/32 to 10.0.0.6/32 peer 192.168.108.206 \
    main group "modp1024" quick group "modp1024" \
    psk "my-tunnel-is-private"
EOF
chmod 600 /etc/ipsec.conf

Slave, puffy208

Loopback

doas su -
cat << 'EOF' > /etc/hostname.lo1
inet 10.0.0.8/32
up
EOF

Enable IPSEC & IP Forwarding

cat << 'EOF' >> /etc/sysctl.conf
net.inet.ip.forwarding=1
net.inet.gre.allow=1
EOF

rcctl enable ipsec isakmpd
rcctl set isakmpd flags -K

IPSEC

cat << 'EOF' > /etc/ipsec.conf
ike esp tunnel from 10.0.0.8/32 to 10.0.0.6/32 peer 192.168.108.206 \
    main group "modp1024" quick group "modp1024" \
    psk "my-tunnel-is-private"
EOF
chmod 600 /etc/ipsec.conf

Slave, puffy209

Loopback

doas su -
cat << 'EOF' > /etc/hostname.lo1
inet 10.0.0.9/32
up
EOF

Enable IPSEC & IP Forwarding

cat << 'EOF' >> /etc/sysctl.conf
net.inet.ip.forwarding=1
net.inet.gre.allow=1
EOF

rcctl enable ipsec isakmpd
rcctl set isakmpd flags -K

IPSEC

cat << 'EOF' > /etc/ipsec.conf
ike esp tunnel from 10.0.0.9/32 to 10.0.0.6/32 peer 192.168.108.206 \
    main group "modp1024" quick group "modp1024" \
    psk "my-tunnel-is-private"
EOF
chmod 600 /etc/ipsec.conf

Full IPSEC Example

cat /etc/ipsec.conf

#
# https://man.openbsd.org/ipsec.conf.5
# http://www.kernel-panic.it/openbsd/vpn/vpn3.html
# https://www.packetmischief.ca/openbsd-ipsec-tunnel-guide/
#
# ike [mode] [encap] [tmode] [proto protocol] \
    # from src [port sport] [(srcnat)] to dst [port dport] \
    # [local localip] [peer remote] \
    # [mode auth algorithm enc algorithm group group] \
    # [quick auth algorithm enc algorithm group group] \
    # [srcid string] [dstid string] \
    # [psk string] [tag string]

# mode:   active (default), passive, dynamic
# encap:  esp (default), ah
# tmode:  tunnel (default), transport
# mode:   main (default), aggressive -> this is phase 1
# quick:  -> this is phase 2


# Var

local_gw    = "MEINE-PUBLIC-IP"
local_net   = "MEIN-NETZWERK/MASK"

auth1       = "hmac-sha1"       # hmac-sha1, hmac-sha2-256, hmac-sha2-384, hmac-sha2-512
enc1        = "aes-128"         # aes-128 (=aes), aes-192, aes-256, blowfish
group1      = "modp3072"        # modp768 (g1), modp1024 (g2), modp1536 (g5), modp2048 (g14), modp3072 (g15), modp4096 (g16), modp6144 (g17), modp8192 (g18), ... (g30)
time1       = "3600"            # in Seconds, or 10m, resp 12h

auth2       = "hmac-sha2-256"   # siehe oben
enc2        = "aes-128"         # siehe oben
group2      = "modp3072"        # siehe oben
time2       = "1200"            # siehe oben


# Tunnel to Remote

remote_gw   = "DEINE-PUBLIC-IP"
remote_net  = "DEIN-NETZWERK/MASK"
key         = "super-huper-secret-key""

ike dynamic esp tunnel from $local_net to $remote_net peer $remote_gw \
main    auth $auth1   enc $enc1   group $group1   lifetime $time1 \
quick   auth $auth2   enc $enc2   group $group2   lifetime $time2 \
srcid $local_gw \
psk $key

ike dynamic esp tunnel from $remote_net to $local_net peer $remote_gw \
main    auth $auth1   enc $enc1   group $group1   lifetime $time1 \
quick   auth $auth2   enc $enc2   group $group2   lifetime $time2 \
srcid $local_gw \
psk $key

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