fix: fall back to binary presence when netfilter capability checks both fails - #1281
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fix: fall back to binary presence when netfilter capability checks both fails#1281thomasferrandiz wants to merge 1 commit into
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…th fail SupportsNFTables() runs `nft --check` via exec, which requires CAP_NET_ADMIN even for a dry run. On systems where iptables is absent but that capability is unavailable at detection time, both SupportsIPTables() and SupportsNFTables() return false, causing ensureBackend() and SetupIPMasqForNetworks() to unconditionally default to iptables — which then also fails. Add IPTablesBinaryAvailable() and NFTablesBinaryAvailable() (LookPath only, no kernel access required) as a second detection tier. When both full checks fail, binary presence breaks the tie: if the iptables binary is absent but nft is present, select the nftables backend. Signed-off-by: Thomas Ferrandiz <thomas.ferrandiz@suse.com>
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Summary
IPTablesBinaryAvailable()andNFTablesBinaryAvailable()topkg/utils— lightweight PATH checks that require no kernel accessensureBackend()(portmap) andSetupIPMasqForNetworks()(ipmasq) to use these as a fallback detection tier when the full capability checks failProblem
Closes #1280
Auto-detection of the nftables backend fails on systems where iptables is not installed, even when nftables is fully available.
SupportsNFTables()callsknftables.New(), which runsnft --checkvia exec. That requiresCAP_NET_ADMINto connect to the kernel nftables subsystem via netlink — even for a dry run. When the process lacks that capability at detection time,SupportsNFTables()returnsfalse.The detection logic was: