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authorGuilhem Moulin <guilhem@fripost.org>2020-05-18 14:28:53 +0200
committerGuilhem Moulin <guilhem@fripost.org>2020-05-18 14:28:57 +0200
commitf3e90041c28a74c94d06f419889691f533422c2f (patch)
tree156dd487aad3a5ffdd84317d5de9abad6e63e2ae /roles/common
parent61ba2a2fe12ffd5578429dfe1d354a1c5d16517a (diff)
Firewall: note on reqid matching.
To be done when we upgrade to Bullseye for more fine-grained control.
Diffstat (limited to 'roles/common')
-rwxr-xr-xroles/common/templates/etc/nftables.conf.j27
1 files changed, 4 insertions, 3 deletions
diff --git a/roles/common/templates/etc/nftables.conf.j2 b/roles/common/templates/etc/nftables.conf.j2
index 2261994..098a66d 100755
--- a/roles/common/templates/etc/nftables.conf.j2
+++ b/roles/common/templates/etc/nftables.conf.j2
@@ -61,9 +61,10 @@ table inet filter {
# https://serverfault.com/questions/971735/how-to-match-reqid-in-nftables
# https://blog.fraggod.net/2016/09/25/nftables-re-injected-ipsec-matching-without-xt_policy.html
# (We can't use marks to match post-ESP decapsulation here because that doesn't work well with UDP
- # encapsulation.)
+ # encapsulation.) We'll also pin the reqid to the lowest address byte in ipsec.conf(5); that way
+ # peers can't impersonate each other.
meta l4proto esp accept
- # ipsec in ip saddr {{ ipsec_subnet }} ip daddr {{ ipsec[inventory_hostname_short] }} accept
+ # ip saddr {{ ipsec_subnet }} ip daddr {{ ipsec[inventory_hostname_short] }} ipsec in reqid $i accept
ip saddr {{ ipsec_subnet }} ip daddr {{ ipsec[inventory_hostname_short] }} meta secpath exists accept
# rate-limiting is done directly by the kernel (net.ipv4.icmp_{ratelimit,ratemask} runtime options)
@@ -110,7 +111,7 @@ table inet filter {
# secpath existence here, because by the time we see a packet to
# 172.16.0.0/24 we don't know if it'll be encapsulated
meta l4proto esp accept
- # ipsec out ip saddr {{ ipsec[inventory_hostname_short] }} ip daddr {{ ipsec_subnet }} accept
+ # ip saddr {{ ipsec[inventory_hostname_short] }} ip daddr {{ ipsec_subnet }} ipsec out reqid $i accept
ip saddr {{ ipsec[inventory_hostname_short] }} ip daddr {{ ipsec_subnet }} accept
meta l4proto { icmp, icmpv6 } accept